Hey guys,

Well, I just sold my motor/tranny a couple days ago and my car is sitting in my fathers garage awaiting it's fate. I've got big plans for the car that will start coming together over the course of this fall/winter. Right now I'm in the planning stages of what potentially will become an 8 second race car. The chassis will be done professionally by a local guy who has seen several cars into the 7 second range now.

The motor will be a 632 ci BBC. If my estimates are anywhere close, it should be in the ~900+ hp neighborhood on motor. It will take advantage of an NOS pro-fogger system as well. I've pretty much set my combo, with the exception of connecting rods. Me and my dad are debating whether I should go aluminum or billet h-beam 4340. I say aluminum, because from my understanding, they will hold up better to heavy doses of N2O. Any input here would be appreciated though.

Now onto the question that originated this post. My biggest ? right now is what transmission will best suite my application. I know plenty of guys going that fast on powerglide trannies. My question is, can it be done on a TH-400 that's properly built? After playing with some numbers, it seems like I'd have to run a 5.14 gear and rev to 8,500 rpm to make use of a powerglide transmission. Even then, the motor falls below stall speed at the shiftpoint(figuring ~5,500 stall on spray). With a turbo 400 on the other hand, the steeper, close gearing keeps the motor in it's powerband(5,500-7,800) much more without having to shift up above ~8,000 rpm.

Anyhow, you see my dilemna, just thought maybe someone could help?

BTW, my target date for completion of this car is the first week of august next year.

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79' Z28...

I am of the opinion that a TH400 is good for about 800 pound foot of torque if it is in good shape.

I say this b/c I think that I read somewhere that the 80 in the 4L80-E electronic O/D tranny stands for 800 pound foot and it is just a 400 with an O/D unit built into it! pdq67

must have forgotten about me....

Unless the car picks up a whole bunch of weight use a glide you don't need the lower first gear. What block do you have? you might have trouble swinging an alum. rod. Alum rods need to be changed at regular intervals unlike steel ones.

I worked at a transmission shop for a couple of years and maintained a THM400 for a guy running a 350CID motor with nitrous. We rebuilt his transmission about every 3 runs. Nothing ever failed, but the clutch packs would become glazed and burned.

-dnult

Brian - Didn't forget, just needed the $$$ now to take care of some things. Sorry dude.

Oger - The car will likely end up around 3,000lbs. with me in it. The problem I see with a glide is all at the shift point. The glide will drop my rpm down below stall speed at the shift point, and I'm pretty concerned about that. I have talked to a couple guys using turbo 400's in low 8 second cars and it sounds like they are holding up pretty good. As far as rods go, any suggestions on what to use then? Seems the only thing I can find would be an Oliver H-beam rod. That one's gonna hurt the ole penny book. I do realize that aluminum rods will only last a couple seasons, but for the money(~$500), it's hard to pass on.

Dnult- Every three passes? What kinda power was he making? How heavy a car? I've talked to two guys in the 8's and they both told me they get a season out of a turbo 400.

Thanks guys, keep the opinions/thoughts coming.

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79' Z28...

I know a guy with a 468" BBC 69 Firebird that runs 9.2's on the motor. He uses a TH400 that was rebuilt "on the cheap" with only the essential HD parts. He leaves the thing in drive and lets it shift itself. He's had no problems yet and has been running the combo since last fall. I'm not sure if he went through the trans over the winter or not.

I don't understand your concern with the shift rpm. they all do that the engine will immediately go to the stall of the convertor if it's high enough. A 468 will not compare with the amount of torque you will make. Oliver rods are the best and if you ever change them they are so pretty you could hang them on the wall as a work of art.

Joe, i understand, although i would have appreciated an e-mail telling me. I didnt even know you had it out of the car.

I work with an automotive machinist who has 30+ yrs experience in the feild, and well knows his stuff. So i get alot of insight from him, and i usually ask about the equipment he would use in High Power, High RPM motors.
So personally i'd consider Oliver, or Crower Billet I-beam for the rods. Skip the aluminum ones, they are light, but you're going to be chucking them alot, unlike steel rods which will last alot longer. Pro's use aluminum in alot of cases, but they also are not worried at all about cost for replacements, and they break down the motors after every event.
Aluminum rods call more head to piston clearance also, becuase they stretch more on the exhaust stroke, and can hit the head if the clearances are to tight.

One question of mine is, if you want to see high RPMs, they why the huge stroke? I'd personally go for a big bore (4.630" or so) and reletively small stroke, like 4.25". You're going to have a trans brake, and spray it off the line, so i dont think you'll need the big stroke.
What kind of heads and intake are you using on this thing?

Why not use a Jerico or Jeffco transmission? You said that you would miss shifting...and this would alow yoy to keep the shifting in it. You'd use a V-gate and super stiff clutch (Mcleod race clutch comes to mind).
If you're set on an Auto, i see no reason why you shouldnt use a Glide, they can be built stronger, and since you're spraying off the line, and will have a brake, i dont think the extra gear would do you any good.

Are you going to race in a prostreet class? Are you going to attempt to use this on the street at all, or just trailor it?

Brian,

It was sorta a bang bang deal. Cash one day, motor out the next. I didn't know you were that interested or I woulda let ya know.

Anyways, enough of the personal stuff.

The more I think about it, the more I think I'm gonna go ahead and try the Oliver rods.

I wasn't gonna go into details on the motor yet, but since you guys are curious:

WP Merlin CNC'ed block
4.600" bore x 4.75" stroke
Diamond custom nitrous piston, 13.5:1 w/118cc heads
Callies crank, Oliver rods
AFR 357 CNC'ed heads
Dart Tunnel Ram, Dual 1250 Dominators
Comp Cams Prostreet grind #11-727-9
(.847"/.792" lift w/1.8 rocker, 286*/302* duration @ .050", 112 LSA)
MSD pro-billet w/7 series box and HVC coil(considering crank trigger setup, but undecided)
Cook's Custom headers, 2 1/4" primary w/4" collector, 4" bullet mufflers
NOS pro-fogger setup, motor will be built to take 400-500hp setup.

Now, why the big stroke? Well, with a 4.25" stroke, and 4.6" bore, I'd have to rev the motor about 1,000rpm higher to make the same power level. My shiftpoints with the above configuration will be ~6900-7100 rpm, as opposed to ~7900rpm with the 4.25" stroke.

Don't think in the realm of street car limitations here. This is a race car.

Chassis/rear doesn't have a real direction yet. With a couple options on the chassis construction and the rear end housing.

Jerico/Lenco/etc. are a bit pricey for me, and I'm not the best gear rower there ever was anyways. This isn't a street car, so shifting gears isn't the #1 priority. The name of the game here is how fast can you go, and more importantly, how consistently. I'm gonna talk to my buddy's friend this weekend that has a 8.60's car. He runs a turbo 400 in his car and sprays the **** out of it, and see what he thinks. Someone sell me on a powerglide http://www.camaros.net/forum/wink.gif. Because frankly, if you convince me it'll work better, I'd rather use it because of weight/power loss of the 400.

Anyways, I'm getting long winded. That's all for now.



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79' Z28...

Joe,
I thought you wanted more RPMs, now the long arm 4.75" stroke makes sense.
Personally i think 2500cfm total is too much, you'd probably make more power in that RPM range with a tall Dart single plane manifold and One 1250cfm Dominator or King Demon. It'll save you alot of money, and the engine probably wont need any more CFM, figure out the engine's estimated volumetric effeciency then calculate.

I dont meen to pick apart your combo, but just a few suggestions, i'm assuming you're going with a solid roller, so why a Comp grind? Read up on what experiences people on the chevelle forum have had with Comp lifters.
My suggestion would be to look at Crower, ultradyne or Reed Cams, with crower severe duty cut-a-way lifters. Spend your money on the best lifters you can buy, dont cheap yourself on that, becuase a lifter failure will kill your engine.

The machinist I work with (he's been around along time, and have worked on alot of engines from full race to stock) likes crank triggers, and he suggested i consider one becuase they do make more power.
Another thing to consider is 16V or 18V ignition, (make sure everything is complatable, and you'll have to use resistors that drop the voltage for everything thats made for 12V. More voltage will make more power, and will allow you to run larger plug gaps. Just something to consider.
My personal choice for the rear would be a spool, since it will see no street use. You'll need some large gears also.
Full cage, at the level you want to race, you'll need a certified chassis, so find a good welder/chassisman and become good friends with him!
If you'd rather use a glide, then use one. You'll hook up easier, becuase think about this, how much gearing do you really need to get moving...what we have here is a light car (or will be) a very torquey engine, a trans brake (so you're launching in your RPM range) and Nitrous! Too much gear and you'll be breakin the tires loose alot i would think.

Think of what kind of combo this guy has, if he has a heavier car, less motor, less rear gearing, then the TH-400 was probably his best choice.


[This message has been edited by CamaroNOTcamero (edited 07-04-2002).]

The car will be 25-1 certified(good to 7.49 I believe).

I will be a round tube frame from the front subframe back. Gonna use a 12-pt cage. Everything will be mild steel to keep down cost. Suspension will be a 4 link with alston shocks. The front subframe will remain stock for now. The car will get 33x18 Goodyear slicks out back. Rear end will be a 9". Strange spool, aluminum pig, 4.56 gears, strange 35-spline axles. The only thing undecided there is whether to upgrade to a FAB 9 housing by Chris Alston.

As for the cam, that's just the cam grind. I can use any lifter I want. I unlike some around here, DO like Comp, and see alot of my customers making great power with their cams.

Carbueration is a tricky setup. I am convinced that a properly tuned tunnel ram setup WILL make more power above 6,000 rpm. I am also convinced that a 1,400hp motor will drink every bit of 2,500 cfm @ 7,500rpm. It may be a bit over carbuerated on motor, but this motor is really gonna be meant to run best on spray.

I'm fairly convinced on the glide. The guy who I'm gonna talk to this weekend with the 70 1/2 camaro that's running 8.60's uses a 400. I wanna find out why. His chassis is the same as mine will be. He is using an EFI 406 that makes about 900hp on motor, and around 1,300hp on spray. Not sure what kinda gearing he has, but I'll know more this weekend.

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79' Z28...

You need to remember a 406 even with juice will not be in the same class as you when it comes to torque. You simply don't need the extra gear of a 400. Most 3000lb race cars are faster with a glide than a 400 if they have enough convertor, mine was. The tunnel ram will be a little troublesome to set up but once it's right you will love it with your combo.

CNC,
If you are referring to me, you are right b/c my memory is just about as long as my left hand index finger, He, He!! We are having too much fun.

The 400 is up there with the 727 and C-6 old style three speeds. Imho. pdq67

PDQ, nope wasnt, but i have a feeling you're messing with me http://www.camaros.net/forum/biggrin.gif

Joe Build it not only for top end power, but to have the most average power that you can. Take the RPM range the motor will work in, and build it to have the most average power in that RPM rnage. The HP peak is not as important as having more torque at the bottom of your RPM range, thats why i suggested the single plane with one 1250 carb. The nitrous system brings in its own fuel with the nitrous, and you will have to jet higher, but i dont think it's going to need an extra carb, i could be wrong though, so i suggest you find out what the motors volumetric effeciency will be at the HP peak, and on the spray.

No, I'm not messing with you. It's just that I get ta rambling on and people tell me stuff and I remember it just about as long as my sawed off left-hand index finger, that's all. Then I repeat myself!

I "NV" people with steel-trap type minds! Wish I had one, thats all. Have a nice day. pdq67

PDQ, what i meant was you cant tell if you're joking on the internet or not.
I have a crappy memory also, so dont feel to bad! I hold in car stuff like a trap door, and well everything else is kinda...i forget.

He, He!!! pdq67

I know this isn't concrete or anything. But, using DDyno2k, I come up with 762 lb-ft @ 5,500(stall speed) rpm w/single plane/1250 cfm. With the Tunnel Ram/2500 cfm nets 811 lb-ft @ 5,500 rpm.

On spray, I'll have torque to burn.

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79' Z28...

Try a tunnel ram with 1250cfm on dd2k, to see if its the tunnel ram, or the extra cfm that's doing it.
DD2K always makes more power with more CFM, becuase of the way it is designed, but we both know that in real life this is not true.

Using DD2k, using a baseline of 4.6" bore, 4.75" stroke
AFR 357 magnum CNC heads 2.30/1.90 valves.
Single plane
1250 cfm
Race "stepped headers"
And the Comp grind you had in the previous message i get:
869HP at 6500rpms
760TQ at 5500rpms

Now to help out i'm going to try a few cams for you:
Using crower #01489 (108 LCA, 284/288 dur at .050") i get:
859HP at 6500rpms
773TQ at 5500rpms

Using crower #01487 (107LCA 270/276 Dur at .050")
846HP at 6500rpms
800TQ at 5000rpms

You really dont need such a big cam, the only reason i had HP drops in this (even though they are minute) was becuase the smaller cams had less lift. You might have clearance problems with dome pistons and very large lift dur, and you're making alot more TQ with the smaller ones, while keeping very close at the HP.
David vizard wrote in one of his books (the title slips my mind at the moment) That 10Ft lbs or TQ in the lower RPM range (in this case the stall RPM) will accellerate faster then 10HP in the top end, becuase the top end is just that, the end. Is the rest of the RPM range that gets you moving through every shift.

You actually dont have TQ to spare, you'll be using all of it to get moving fast!

I tried the tunnel ram without the added CFM to see if it was the ram that was helping power, and it was not. I lost one HP, my guess being becuase you're not in the tunnel rams RPM range.

[This message has been edited by CamaroNOTcamero (edited 07-05-2002).]

Here's another tid bit i found out:
with a 33" tire and 4.56 gears, shifting at 7000rpms with a glide, you'll be doing about 85 MPH, which when you shift will drop your RPMs to 4000rpms, ignoring Stall speed.
So you will need you're mid range to keep you moving fast, dont ignore the bottom end of your RPM range of operation.

But you can't ignore stall speed. So really when the shift happens, I'll be dropping to ~5500 rpm, right at my torque peak. And ya, those other cams make a little more peak torque, BUT, they are ground on to tight of a lobe center for me. Remember, this is a nitrous motor. The crowers are 107/108 LCA'a. The comp grind is a 112. Also, those lift numbers are with a 1.8 rocker, I could always tone it down with a 1.7 if there is piston/valve clearance issues.

I'm not completely concerned with peak torque because nitrous motors make RIDICULOUS torque to begin with. My baseline motor with Tunnel Ram, 2500cfm worth of carbueration, 14:1 compression, AFR 357's, etc, makes 800 lb-ft of torque @ 5,500 rpm. On a 500hp dose of spray, It makes 1276 lb-ft of torque at 5,500rpm. So, like I said before, I've got torque to burn. It will take a perfectly setup car, and a good track to make this thing hook IMO.

Remember when your thinking about this motor, that the N/A numbers aren't what matters here. It's a race motor, that will be built to run on heavy doses of N2O, which changes everything.

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79' Z28...

Torque is whats moving the thing, and i dont understand how you have Torque to burn? You'll be using all of it!
Crower Has wide LCA "nitrous" grinds as well.
Reed Cams has even more options, they have a lobe catalog, and you pick one or two lobes that you like and they grind it to whatver LCA you want.

[This message has been edited by CamaroNOTcamero (edited 07-06-2002).]

Joe, the TH400 can be built to take whatever you throw at it if built right. It is probably the strongest automatic ever installed in a passenger car. I copied the following form Art Carrs site.

A powerglide is most useful in light cars with high horsepower to weight ratio. A powerglide as built by Art Carr Performance products allows the torque converter to multiply torque for a longer time. Torque is what accelerates the vehicle forward. Three speed transmissions with low rear end gears don’t allow the maximum torque multiplication available from the torque converter. High horsepower (800 and up) to weight (2500 and down) ratios benefit from the powerglide.

However, with the power and torque you will be making, I'd go with a 'glide. Your motor should make monsterous torque and the 'glide will let you stay in the "band" longer as well as having to shift only once helps consistency. Also I'd go with steel rods unless you plan on tearing the motor apart frequently. Check out this site on trans.
www.coanracing.com/index.html (http://www.coanracing.com/index.html)

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409SB, TH350, 12bolt 4.10
7.18 @ 95 on premium pump gas

Gear wise, Powerglide: Fast and Faster! http://www.camaros.net/forum/smile.gif

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78 Camaro hyd cam 406
TH350-3.23 gear
11.86 ET
116.7 MPH

Joe,
I don't run many autos anymore. But when I do it has been the Turbo 400. I blew a LOT of TH350s and vowed not to run anymore of them. The last certified 69 car I bought came with a powerglide and 5.14s, I never got to run it, I sold the car to someone who wanted to pay me more than it was worth to me last year.

Just a note while you are building the TH400 make sure to use a manual valve body. The stock TH400 will not allow you to rev past about 6,000 or 6,500. If you try they will shift themselves into second gear on their own, very very annoying.

Dave

Dave,

I'm actually leaning towards the PG. It is the lightest, uses the least power, and is strong as hell in a light car. I'm curious why you say turbo 400?

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79' Z28...

Joe,
On a street car I like the turbo 400. I grew up in the 70s, (some would argue I have yet to grow up). In the mid 70s all the muscle cars were just used cars and the high school parking lots were full of Ss Chevelles, Camaros, Novas, Challengers and Cudas. My high school parking lot looked very close to what some people today would call a car show. We were kids and didn't know how special these cars would one day be, they were just used cars and they were fast. The TH400 was a performance auto trans back then, even the Z/28 came standard with it and a small block in front of it, before they killed it in 75. No one ran powerglides unless they were waiting to come up with the cash to swap a 400 or a 350 with a kit into their cars. I've destroyed so many turbo 350s, but never hurt a 400 even behind big block cars. I much prefer Muncies to anything else for the street though, just my preference, I like shifting. The glide is probably a very good choice on a drag car, it certainly is a popular choice and is probably a good choice since that's what you appear to be building. The 400 is just what I grew up with and it never let me down.

Dave

Dave,
I tend to agree the turbo 400 would be a better trans for a true street car. This is not a street car though. I think I'm gonna go with the Hughes 2-piece PG.

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79' Z28...

before you settle on the huges take a look at these www.artcarr.com (http://www.artcarr.com)