My new 383 dynoed on the stand at 440 HP. After it was installed, it was dynoed on the chasis dyno and only got 292 RWHP. Is it normal to lose 150 horsepower through the drive train? I have a 700 R4 tranny. They tried to tell me that it lost a few horses because the tires were slipping on the rollers and 292 HP was about right after drive train loss. How is it possible to lose traction once the car is up to speed/RPM on the dyno's rollers???? The tires are 245-60's and should be wide enough to maintain a constant grip. I thought that traction wasn't an issue if the pull is gradual. It was a Dynojet dyno if I am correct. If the normal ratio of power loss is 20-25%, I figure at most I would lose 110 HP through the drive train. That should still give me 330 HP at the rear wheels. I know they didn't open the hood and use a fan to simulate wind at high speed. I am not sure if that would make a significant difference anyway. Please help! Any comments are appreciated. :( Thanks, DeAngelo

I have normally calculated loss with a 700r4 closer to 15% per drive wheel. Posi-trac rear? 30%. However I feel that number is a little low....HMMM

what changes are there between the engine on the engine dyno and chassis dyno? It was dynoed on an engine dyno, not by a computer dyno deal, right? Was the engine dyno with open headers, etc.?

The numbers are low and depending on how you answer the questions I might try another dyno.

Jody

I've done hundreds of dyno pulls on a Dynojet 248 and have never seen tires slip on the dyno. Tire slip would show up as a huge anomaly on the graph. We've dynoed some 440 hp 383's from a local builder and they also run about 290-300 hp to the rear wheels.
Here's some things to ponder:
What is different about your engine as it sits in the car and as it was mounted on the engine dyno? Did you put the dyno headers in your car? Did you put the dyno mufflers on your car? Did you mount any more belt driven accessories? Did you use the same cold air to the carb as the engine dyno did? Did you try locking the converter? Were your tires fully inflated?

Corrected (perfect air/ altitude) #'s from engine dyno, vs real world conditions on chassis dyno maybe?
What is you altitude and air conditions where you did the chassis dyno test? Do you have a DA reading from both dyno tests?

How did the air fuel ratio look?

Lets get some more specs on the motor> Also...from what I have seen 290 to 320 to the wheels seems about norm for street bound 383's going through an auto.

I've had my car on two "roller" chassis dynos and it slipped on both, wasting my tires and my time.
Maybe find someone with a Dynapack. No possibility of tire slip on these and sensitive enough to see load on the alternator from switching on headlights (so they claim).
http://www.dynopack.co.nz/

http://www.youtube.com/watch?v=RJtV5shYoAs
http://www.youtube.com/watch?v=_WiS_o007Ew (that's me!)

WOW! Thx! Great answers! The original engine dyno was with open 1 3/4" headers and no mufflers. It also had no accessories attached. On the chassis dyno, the car was as it is on the street. I have AC, power steering, non-electric fan, alternator, 1 5/8" Thorley Tri-Y headers etc. And if it did slip, it didn't appear so on the dyno graph. I just thought that it was a HUGE difference in HP. I guess the fuel mixture was right. I am not good with that type of thing. It was between 12 and 14, whatever that means. :) And yes, it has a posi-traction rear end. I would imagine that it would also cause a reduction in HP. I have a pic of the chassis dyno run but don't know how to attach it. I would love to do so if anyone could help me with posting it. I will have the engine dyno pic later this week. I am in Virginia and it was about 60 degrees when they chassis dynoed it. I also noticed no anomolies in the dyno graph. It was very smooth. Makes me think that there was no slipping. And the tranny has a 3,000 non-lockup stall if that helps. Thanks again, DeAngelo

I know of a camaro that had 620hp +/- and dynoed 500rwhp they swapped in an automatic with 5,500 stall and made 440 same motor same car and went 2-3 tenths faster with 60 less rwhp.

If you dont have a decent air filter, exhaust / fuel / ignition system like on the dyno then youre leaving a ton of power on the table.

I've had my car on two "roller" chassis dynos and it slipped on both, wasting my tires and my time.
Maybe find someone with a Dynapack. No possibility of tire slip on these and sensitive enough to see load on the alternator from switching on headlights (so they claim).
http://www.dynopack.co.nz/

http://www.youtube.com/watch?v=RJtV5shYoAs
http://www.youtube.com/watch?v=_WiS_o007Ew (that's me!)

Steve,

I would say they didn't know how to strap the car on the dyno, and at what position to place the tires on the roller. I've made well over 800 rwhp on a Dynojet with no tire spin and street tires.

Jody

Steve,

I would say they didn't know how to strap the car on the dyno, and at what position to place the tires on the roller. I've made well over 800 rwhp on a Dynojet with no tire spin and street tires.

Jody


What I was thinking too.

I've had my car on two "roller" chassis dynos and it slipped on both, wasting my tires and my time.
Maybe find someone with a Dynapack. No possibility of tire slip on these and sensitive enough to see load on the alternator from switching on headlights (so they claim).
http://www.dynopack.co.nz/

http://www.youtube.com/watch?v=RJtV5shYoAs
http://www.youtube.com/watch?v=_WiS_o007Ew (that's me!)
I watched your dyno video labled "thats me".
Who is the person standing in front of the car at full throttle while running on the dyno loose enough to slip the tires?
Have they never seen a car come loose and fly off the dyno?
Looks like a foolish place to stand.

My point exactly. How could the tires slip when the power is applied gradually???

My point exactly. How could the tires slip when the power is applied gradually???

actually, it's only gradual up to the starting rpm, then it's mat the throttle! But placement of the tire on the roller and how the car is strapped down make a huge difference in whether the tires will slip or not.

Jody

Good point, Jody. Thank you for the response. Overall, I get the impression that 292 at the wheels isn't too bad. I justthought that the difference between the 2 dynos was HUGE! I didn't expect such a big drop going from engine dyno to chassis dyno. I just want to be faster than a rice burner or a new Mustang GT. :)

How were the torque numbers?Harvey

What are the details on your combo........compression, cam, heads and so on? I am pulling together ideas for my 383 right now and would be interested in what you have in yours. Thx!
Tom

The torque numbers were a max of 282 at about 5000 RPM. At 3500 RPM, torque was 200 at the wheels. At 4000, it was 250 at the wheels and went up to a max of 282 at approx 5000. Don't get me wrong, the engine has nice power. I can SCORCH the tires and it pulls HARD. I just want every horse I paid for. :) I expected 330 at the wheels with an engine that produces 440 on an engine dyno. I wonder what it will do in the quarter or 0 to 60. I have a printout of the chassis dyno but can't upload it without a link.

And Tom, my compression is 9.5 to 1. I have a Professional Products Hurricane intake (Edelbrock Air Gap RPM copy), Holley 770 CFM Avenger, Lunati cam with 235 intake and 240 exhaust duration with a 490 intake and exhaust lift at .050 with 112 degree lobe separation. The heads are the Holley aluminum ones. The heads and cam were part of the Holley SytemMAX 2 package. My tranny is a 700R4 with a 3000 stall and a 3.73 Posi rear. My tires are cheap no-name 245/60 14's!!! I can melt those cheap tires! I am going to buy some 275/40 17 inch Nitto 555's soon. Hope that helps, Tom.

DeAngelo

This thread is depressing.


:sad::(

HAHAHA Why is that, Doug? Is it because a 2007 stock luxury car or sedan can put down 300 to the rear wheels with no problem??? :) I saw Horsepower TV yesterday and they chassis dynoed a new Cadillac and it put down 327 to the rear wheels bone stock!! :)

:D

http://i12.photobucket.com/albums/a224/sc68z28/dyno_1.jpg

Sick ---Bill.

This thread is depressing.


:sad::(

Why? Do you race on a dyno or on a track? My roller cammed 355 only put a little over 340 to the tires on a Mustang dyno but it still runs 11.30's at 120 in a 3,350 pound car.

Let's see how his car does at the track! :beers:

I was right with you until you posted your specs...

Something ain't right.

My car, with 10 degree's less cam and a smaller carb, pulled (on a dynoJet) 293 peak HP @ 5200, but... 300 Ft-lbs @ 2000 rpm (beginning of pull) and 400 ft-lbs peak torque, at 4200! And still holding 300 ft-lbs @5800.

I watched your dyno video labled "thats me".
Who is the person standing in front of the car at full throttle while running on the dyno loose enough to slip the tires?
Have they never seen a car come loose and fly off the dyno?
Looks like a foolish place to stand.

It's a Dynapack dyno!
The rear wheels are removed and the dyno is bolted to the axles. Impossible for the car to go anywhere.
Did you watch this vid and notice no wheels?
http://www.youtube.com/watch?v=RJtV5shYoAs

Steve,

I would say they didn't know how to strap the car on the dyno, and at what position to place the tires on the roller. I've made well over 800 rwhp on a Dynojet with no tire spin and street tires.

Jody


Yeah, that's quite possible. ;)
Two different dynos and two different operators wasn't too encouraging to try again though.

HAHAHA Why is that, Doug? Is it because a 2007 stock luxury car or sedan can put down 300 to the rear wheels with no problem??? :) I saw Horsepower TV yesterday and they chassis dynoed a new Cadillac and it put down 327 to the rear wheels bone stock!! :)

Ya, that's part of it.

292 at the wheels doesn't inspire me much.

:(

I was right with you until you posted your specs...

Something ain't right.

My car, with 10 degree's less cam and a smaller carb, pulled (on a dynoJet) 293 peak HP @ 5200, but... 300 Ft-lbs @ 2000 rpm (beginning of pull) and 400 ft-lbs peak torque, at 4200! And still holding 300 ft-lbs @5800.

Something ain't right is right, 300#ft @ 5800 rpm would be 331 rwhp...

I was right with you until you posted your specs...

Something ain't right.

My car, with 10 degree's less cam and a smaller carb, pulled (on a dynoJet) 293 peak HP @ 5200, but... 300 Ft-lbs @ 2000 rpm (beginning of pull) and 400 ft-lbs peak torque, at 4200! And still holding 300 ft-lbs @5800.

He is losing alot with that 700R4 compared to your stick.

Good point, 67 Plum. And I am looking to find some other shop to dyno it for me and perhaps tune it correctly.

You can easily lose 70-80 horses with the changes you made by putting the engine in the car. If I make a your motor on EA3.2 and use the dyno setup with just a water pump, dyno exhaust and cold air I get:

RPM···········2000····2500····3000····3500····4000 ····4500····5000····5500····6000····6500
Brake_Tq······298·····334·····410·····415·····425· ····434·····429·····411·····382·····320
Brake_HP······114·····159·····234·····277·····324· ····372·····408·····431·····437·····397
Exh_Pres······.0······.0······.0······.0······.0·· ····.0······.0······.0······.0······.0
Int_Vacuum····.3······.6······.6······.6······.6·· ····.7······.9······1.0·····1.2·····1.3
Vol_Eff_%·····69.3····75.3····87.1····89.6····93.0 ····96.7····98.2····97.6····95.7····91.0
Actual_CFM····165·····224·····314·····375·····444· ····521·····588·····643·····687·····706
Fuel_Flow·····58.9····79.8····112·····133·····158· ····186·····209·····229·····245·····252
A/F_Mix_Qal···100.0···98.7····100.0···100.0···100.0· ··100.0···100.0···100.0···100.0···100.0
BSFC··········.518····.503····.478····.482····.488 ····.499····.513····.531····.560····.634
BSAC··········6.513···6.322···6.009···6.065···6.14 1···6.274···6.455···6.682···7.044···7.977
Friction_HP···18······26······36······48······61·· ····79······100·····125·····155·····203
Mach_#········.179····.223····.268····.313····.357 ····.402····.447····.491····.536····.581
Piston_Spd····1250····1563····1875····2188····2500 ····2813····3125····3438····3750····4063
Piston_Gs·····283·····442·····637·····867·····1133 ····1433····1770····2141····2548····2991
Overlap_%VE···-3.7····-1.9····4.4·····2.8·····2.5·····3.4·····3.7·····3.5 ·····3.1·····2.6
Int_AvgVel····112·····140·····168·····195·····223· ····251·····279·····307·····335·····363
In_InertiaPrs·.1······.6······1.1·····1.6·····2.0· ····2.2·····2.3·····2.3·····2.1·····1.9
In_ResTunPrs··0.0·····.0······.0······.0······.0·· ····0.0·····0.0·····0.0·····0.0·····0.0
Ex_AvgVel·····124·····155·····186·····217·····249· ····280·····311·····342·····373·····404
ExTun_Prs·····.8······.1······-1.2····-.7·····-.6·····-1.4····-2.2····-2.4····-2.1····-1.8

If I add the accessories, 1-5/8" x 24" headers with twin 400 cfm mufflers and raise the intake air temperature by 25 degrees it comes out like:

RPM···········2000····2500····3000····3500····4000 ····4500····5000····5500····6000····6500
Brake_Tq······274·····316·····338·····358·····371· ····377·····367·····346·····314·····253
Brake_HP······104·····150·····193·····238·····282· ····323·····349·····362·····359·····314
Exh_Pres······.1······.2······.3······.5······.7·· ····1.0·····1.2·····1.4·····1.6·····1.7
Int_Vacuum····.3······.6······.6······.6······.6·· ····.6······.7······.9······1.0·····1.1
Vol_Eff_%·····69.4····76.3····81.1····86.5····91.0 ····94.6····95.9····95.2····93.3····88.9
Actual_CFM····165·····227·····290·····361·····434· ····507·····571·····624·····667·····688
Fuel_Flow·····55.9····76.9····98.1····122·····147· ····172·····193·····211·····226·····233
A/F_Mix_Qal···100.0···100.0···100.0···100.0···100.0· ··100.0···100.0···100.0···100.0···100.0
BSFC··········.536····.511····.507····.512····.520 ····.532····.553····.584····.629····.743
BSAC··········6.738···6.431···6.381···6.440···6.53 3···6.690···6.957···7.337···7.910···9.338
Friction_HP···20······29······40······53······68·· ····89······113·····141·····175·····227
Mach_#········.179····.223····.268····.313····.357 ····.402····.447····.491····.536····.581
Piston_Spd····1250····1563····1875····2188····2500 ····2813····3125····3438····3750····4063
Piston_Gs·····283·····442·····637·····867·····1133 ····1433····1770····2141····2548····2991
Overlap_%VE···-5.0····-2.8····-2.4····-1.6····-1.2····-.4·····-.2·····-.7·····-1.0····-1.2
Int_AvgVel····112·····140·····168·····195·····223· ····251·····279·····307·····335·····363
In_InertiaPrs·.0······.5······1.0·····1.5·····1.9· ····2.2·····2.3·····2.3·····2.1·····1.9
In_ResTunPrs··0.0·····0.0·····.0······.0······.0·· ····.0······0.0·····0.0·····0.0·····0.0
Ex_AvgVel·····145·····181·····217·····253·····289· ····325·····361·····397·····434·····470
ExTun_Prs·····1.4·····.3······.3······-.2·····-.6·····-1.2····-1.5····-1.6····-1.4····-1.1


If you lose 20% of the in-car power through the drivetrain, the prediction would be roughly 290 rwhp.

I watched your dyno video labled "thats me".
Who is the person standing in front of the car at full throttle while running on the dyno loose enough to slip the tires?
Have they never seen a car come loose and fly off the dyno?
Looks like a foolish place to stand.

If you look closely, the driver was on the right hand side, so he was actually standing at the rear :D

Seriously though, that's a pretty risky place to be.

If you look closely, the driver was on the right hand side, so he was actually standing at the rear :D

Seriously though, that's a pretty risky place to be.

Thanks, but no it's not.;)

The car CAN NOT MOVE on these dynoes.

Thanks, but no it's not.;)

The car CAN NOT MOVE on these dynoes.

As long as the dyno boxes don't lock up! Can you imagine??!!! :eek: They are a cool dyno as it takes tire slip out of the equation.

Jody

Thank you, Onovakind! I appreciate the simulation. That was VERY nice of you to do! That is why I love this site! If I can help you somehow, please let me know!! I feel much better knowing that I have the HP I should have. What is EA3? Your numbers were almost IDENTICAL to my engine dyno!!! They were off by 3 HP at peak and 5 Ft/Lbs at peak. That is INCREDIBLY ACCURATE!!! That is a HP tolerance of less than 1%!!! The torque numbers were just as accurate. :) Thank you again. This site has never let me down. :) DeAngelo

EA3.2 is Engine Analyzer 3.2 by Performance Trends.

http://www.performancetrends.com/

The rear wheels are removed and the dyno is bolted to the axles. Impossible for the car to go anywhere.
Did you watch this vid and notice no wheels?

I watched, but you can't see the rear wheels in the video and I am not familiar with Dynapack. If there is no way for it to come loose, then I suppose it would be ok. There was a video link a while back where the car came loose and surged forward, just didn't want to see that happen to you.

I watched, but you can't see the rear wheels in the video and I am not familiar with Dynapack. If there is no way for it to come loose, then I suppose it would be ok. There was a video link a while back where the car came loose and surged forward, just didn't want to see that happen to you.

Dyno pack is cool as it's mobile and takes up little room. There's two boxes, one for each rear axle. You jack up the rear of the car, remove the rear wheels/tires and bolt the units directly to the axle.

WOW! dyno was with open 1 3/4" headers and no mufflers. It also had no accessories attached. On the chassis dyno, the car was as it is on the street. I have AC, power steering, non-electric fan, alternator, 1 5/8" Thorley Tri-Y headers etc.

DeAn,
I bet the 1 3/4 open headers were good for 30 hp over the 1 5/8 and mufflers. The accessories probably eat another 20 or so. Add in the drive train loss and you are probably right about where you should be.

Thanks, Bill!! I appreciate your input. All I wanna do is beat a new Mustang GT from 0-60! :) Can I do it? :)

You should have the new Stang cover without any issues. They ususally dyno right at 260 to 275rwhp with the 5 speed. Plus your car should be lighter as well.

Installing a different exhaust than the engine was dynoed with can require different jetting. Did you measure Air/Fuel ratios and try any other jets? Is the carb achieving full throttle in the car? Did you just do a pull or two on the dyno or spend some time tuning it?

My wife's car picked up 100hp on the dyno just by changing jets! We had it pretty good with the old exhaust system but the new system (X pipe) caused it to run super lean (15.4 to 1) to the point where there was a huge power loss. After upping the jets by 7 steps, we finished slightly rich but making good power.
David

Thanks for the vote of confidence, 6D9. Bill, the carb is achieving WOT but changing the jets sounds like a good idea. I am not a carb guy but I will look into that when I find another shop to dyno tune my car properly like it should have been. And maybe the next shop will strap it down properly as well. I am sure they just pulled it without an eye towards tuning although the fuel mixture was checked. It looks to be around 10 to 1 or so through most of the pull. I dunno if that is a good thing as I know little about carbs. Thanks again, DeAngelo

12.7 is supposed to be best under full power. We are at 11.6 which is a bit too rich. 10 to 1 is very rich and you'd probably pick up some power going leaner.

Most of the shops I have been to in Australia have always worked on a one third loss through the drivetrain. One third off 440 is very close to what you have at the wheels.

Just my take on all this, but I'm new to this haul-*** car game. But engines and tools and such I've spent a lifetime with...
A dyno is a tool. A learning tool as much as a measuring. You learned you have losses. Now you need to measure them.
If you change dynos and make changes to your car, you won't know what you netted. If you want to make the most use of this tool, don't muddy it.
Either stick with the same dyno, or go to another before you make changes to the car.
I wish I had time to play with dyno's. I only get to use them at work on great big ugly engines, and it's a rare event then, and all we are after is to prove we can meet spec and didn't strew or spew.
I like real world tests. Go stomp a Stang if that's what you're after.
You seem worried about eliminating tire slippage on the dyno. I don't blame you, but you will have slippage on the track or street won't you?
Later
Tim
77 Camaro 412SBC Brodix T1 CNC,no juice yet, 10.85/126mph
fire ain't lit all the way yet

Good point, Tim. Thanks. And Dave, I made an error. My AF ratio is 13 up to 4000 and then it is 14 and drops after 5000 a bit. Basically, it is 13 to 14. Hope that helps. Also, I would like to have more power than a brand new factory car considering how much I have spent. I hate to see a youngun just buy a car off the show room floor and be faster than a true MUSCLECAR!!! :) Thanks again, DeAngelo

You want your AF ratio between 12.5 to 13 at WOT. I think if you jet it up a bit you should hit right around 300rwhp.

i got pritty much the same setup as you, i think your loss is in exhaust, carb tuning and timing, do you have shortys or longtube headers? what timing you running?

Thanks, 6D9. I will look into that once I redyno it at a diff place. The service at the shop that built my engine is pitiful. The guy is about 30 and has little experience. I need a seasoned mechanic to look at my car and its details. And Jigga99, I have a set of Thorley tri-Y's. They are the best fitting headers I have seen. The Hooker's were 2 inches from the ground and the Headman's hit the steering box. The timing is 36 degrees at WOT if I am correct. Thanks, D

Most of the shops I have been to in Australia have always worked on a one third loss through the drivetrain. One third off 440 is very close to what you have at the wheels.

I've spoken to a few professionals who build and dyno engines and they've said the same 1/3 loss thing too.
But there is no way you can apply this rule of thumb to anything that makes more than 150hp in my opinion.

If that was the case with my 520rwhp on the Dynapack, it would mean I am making 780hp at the flywheel. ..and that would be pure balony!
(780 x .66 (or minus 1/3) = 520)
Even a 25% loss at that power level is being very optimistic.
(693 x .75 (or minus 1/4) = 520)

For me, I'm guessing more like a 15-20% loss.. for my combination of PG & 9". ;)

i had my engine dynoed befor i got it it was turn key and they had the timing at 34, can you check your old engine dyno graph when it was on the stand, for what the timing was set at?

The timing was at 36 degrees. I figured that was good. And what was your HP, Jigga99? Thanks, D

I was talking to a freind that has had two motors dyno'd in the last couple of weeks.

What he as told is that there are a couple of factors that people forget or don't know about.

1) Weather conditions play a big affect on HP numbers. Hot muggy wether will produce less HP than a cool dry day. You need to know all of the weather conditions during the dyno so that you have a base line to compare other tests.

The shop that my friend went to does not perform engine dyno's in the morning on a cold, dry winter day. This is because you will never have a race day with these type of conditions. You may have 500 HP when dyno'd during the winter, but you would never see 500 HP during the dog days of summer.

2) How the engine is brought up to speed, and when the load is introduced. His motor showed 30 HP difference based on how the load was put on the motor.

Most dynos have local weather stations to monitor the conditions. There are several correction factors that account for differences in atmospheric conditions like:
- SAE-J1349 the one that seems to work best! And is used by lots of dyno companies as default.
- DIN 70020 Also popular, and used by people who like bigger numbers! In a lot of conditions it gives figures a few percent higher than the rest.
- EEC 80/1269
- ISO 1585

http://www.dynamometer.fsnet.co.uk/automotive-dyno-correction-factors.htm

Most dynos have local weather stations to monitor the conditions. There are several correction factors that account for differences in atmospheric conditions like:
- SAE-J1349 the one that seems to work best! And is used by lots of dyno companies as default.
- DIN 70020 Also popular, and used by people who like bigger numbers! In a lot of conditions it gives figures a few percent higher than the rest.
- EEC 80/1269
- ISO 1585

http://www.dynamometer.fsnet.co.uk/automotive-dyno-correction-factors.htm

This is true, but I understand that conditions can be changed to "suit" the needs required to make the HP numbers that the job was sold to produce.

You can change anything you want on a dyno if you know how. We once got a 9% power increase on a Datsun 240SX by icing down the intake. The guy wanted to get over 100 hp at the rear wheels so he could brag to his friends. A $1.50 bag of ice from the local market put him over the top.

dean it made 412 on the engine and 300 at the wheels ill take a look at the chart to see at what rpm it was over 5500, timing makes a big diff on how these run,

Good points. Thanks for the feedback. Looking fwd to more Dyno stories. :) D

hit me a msg when you try to dyno again

Don't know when that will happen but I am going to a better shop. I want to go to a place where they are MOTIVATED to achieve more power. I want a true dyno tune. I want a shop to think about changing the jets, playing with the timing, modifying things, etc. I want more power! As it is, the car is in their shop right now and they are clueless as to why there is so much pressure built up and causing this leak.The last time I picked it up and drove home, I turned the car off and there was no leak. 5 minutes later, I heard a "whooshing" sound and thought I blew a radiator hose. There was a vapor that filled the garage. I thought it was antifreeze. Turned out to be an oil leak. I think it was from the rear of the valve cover gasket. I found a HUGE puddle of oil under the car. It was raining and I didn't have room in my tiny garage to check it out. I just took it back to them to fix the next day or so. Oddly, I started the car and drove it to the shop and there was no leak! Weird. It now seems to shoot out oil only under pressure and after I turn the car off. Of course, it didn't do it when I dropped it off. Now I am skeptical if they can find this intermittent problem. I am sooo disappointed. I have spent a ton and have driven it only a few hundred miles. This is the 5th time I have taken it back for some type of leak. They keep making changes and there is still some type of leak. I don't know what is gonna happen next. I am going to check on it today. :( DeAngelo

There is a common oil leak source on the front of the block. On the RF lower corner of the block are two 3/8" threaded holes, the top one intersects the fuel pump pushrod hole. A SHORT 3/8" bolt MUST be in this hole. The hole originally was used for motor mounts in the 55 Chevy, and others. The GM manual says to change the fuel pump you should remove the old pump, hold the pushrod in and screw a long enough bolt into the front hole to hold the pushrod in place. This makes the sometimes difficult job of fuel pump replacement a snap. BUT if a long bolt is EVER tightened down in this hole, the pushrod will be bent!

David

Thanks, Dave. I picked it up yesterday and it is now leak free for now. I am happy for the time being. :) We shall see what the future holds. D

well...


my stock DZ302 pulled 301 rwhp on a Dynojet.
at the time, i was running the correct reproduction Kustom 1968 Headers,
and an AED Holley 830 eliminator, which had a huge spikethat i attribute to no tuning what so ever..

this week, , i put a new 4053 Holley on it (with MacNeishes jetting), and replaced the headers with the correct dated exhaust manfiolds,and a non functional smog setup and the car actually feels faster and will now break the tires lo when the secondaries come in. And that spike is long gone, so i'm going to get it back on the same dyno as soon as I get some time.

There are a few minor tweaks in this motor, but nothing substantial.



http://www.tinypix.com/MyAlbums/PrivateRequest.asp?Rand=5690168&Attachment=0&AlbumID=5264&URL=%2FPhotos%2F200x200%2F1%2Ejpg
http://www.tinypix.com/MyAlbums/PrivateRequest.asp?Rand=7686344&Attachment=0&AlbumID=5264&URL=%2FPhotos%2F200x200%2F2%2Ejpg
http://www.tinypix.com/MyAlbums/PrivateRequest.asp?Rand=9840331&Attachment=0&AlbumID=5264&URL=%2FPhotos%2F200x200%2F3%2Ejpg
http://www.tinypix.com/MyAlbums/PrivateRequest.asp?Rand=9888319&Attachment=0&AlbumID=5264&URL=%2FPhotos%2F200x200%2F4%2Ejpg

if anyone knows how to make this appear large on the screen, they are the dyno sheets for my 302.

thanks

One word: WOW!

my pooint in posting that , is that I think something is holding you back..

my engine has original unported 186 heads, stock Z28 intake,
11 to 1 compression, Predator 30-30 cam (which has advanced ground into is)

at the time of the dyno,,, i had the headers on and a Pypes 2.5 exhaust

point ignition, with the original coil, and repop Packard wires, with vintage greenstripe AC46 plugs.

clearly, i was more concerned about the historical correctness of the car.
i had at least 2 rockers out of adjustment, and no timing work other than setting the dist by ear when I broke the cam in.

the carb was out of the box, and i never touched it other than the 4 corner idle.


since, that dyno, i have the correct carb on it and it is tuned for optimal performance, and I put the OE manifolds back on. which you'd think would slow it down terribly.... but that big holley i had on, must really have been not right becasue now that i have the correct carb on, and timing is right,the car runs stronger across the entire RPM range.

i would expect to see 350-375 rwhp out of your car.... with the way it is setup, considering what i got out of my pure stock Z.

thanks

aaron

Good point, 69z28boy. I agree with you. I am going to take it to another place where I can get a "second opinion". Unfortunately, the next dyno may be different and the conditions may be different. The next shop will do a baseline for comparison then try to dyno tune it. Thanks! D

While I'd love to see those kinda numbers, in this case I disagree with Aaron.

Deangelo, our combos are extremely similar, and ran within 1 HP on a dynojet. Peak power on our mild 383's is at a paltry 5200 rpm or so. HP = torque times RPM, and you can bet that 302 put out that number at CONSIDERABLY more than mid 5k rpm's.

I talked to many members here about dyno numbers. Dynojets generally read lower than many other dynos, and 300 HP to the rear wheels is pretty typical for a mild 383.

lots of good info in this thread!!!

indeed,

my 302 put up 301 rwhp at 6600rpm.

it will take 7600 rpm all day, but it does fall off after 6500 .


i'd really like to see someone build a high compression 383 and install the 30-30 cam or the Offroad 140 cam.

They seem to make great power in a small engine, but rarely do you see someone install them in a 383 or 400

and i agree that going from dyno to dyno is not going to yeild concrete evidence unless you do multiple pulls on the same one.

I didn't have time to do all kinds of tuning on my car, but i will this spring.
i'm interested in seeing just how much reliable power I can tune out of an essentially bone stock DZ302

A
Thanks

aaron

http://home.comcast.net/~onovakind67/DD331dyno.jpg
How about a 331" small block that makes 346#ft @ 4200 and 337 hp to the rear wheels @ 5900 rpm's with a 228°/228° cam and a 2-bbl carb?
Add a set of AFR195's and a 240°/240° cam and it goes to 351#ft @ 4300 with 361 rwhp @ 6200.
Add a 4779 Holley on a Vicjr and it increases to 363#ft A 4600 rpm with 418 rwhp @ 7100.

Thanks, Jim! I feel much better. I understand exactly what you're saying. Thank you, Aaron and Onavakind as well. This is a fantastic thread and I have learned a lot! Now I wish I had that 331 small block! :) DeAngelo

next winter I'm gonna step it up a lil, tho it may take 2 years to do everything I want. Shopping list includes AFR 195 eliminators, hydro roller in the 235& 050 / .550 range, and 900 cfm worth of efi.

Will easily be worth 100 HP @6k at the wheels, without losing much if any low end torque.

Like to see that dyno! D