Gentlemen,

Im "considering" as a winter project, in the never ending quest for more power, of adding a stroker kit to my fast burn 385 (350 CID), and would like some opinions on a few specific questions.

1. Is a standard bore stroker kit available for my one piece rear seal block? I'd prefer a forged crank if available and reasonable. Any suggestions on a brand?

2. 5.7 or 6.0 rods? I know it's been debated, but is there a consensus?

3. Flat tops? dished? The Fastburn heads have 62cc chambers.

4. I'll definitely stick with the hyd roller and the fastburn heads. Any thoughts on a cam? Stick with the HOT cam? I sure like it's manners, but I think I could get away with a bit more duration.

This is strictly a street driven car, with power brakes.

As usual, thanks in advance for all replies!

[ 10-21-2003, 11:07 AM: Message edited by: BPOS ]

If you stay with the hot cam definately get dished pistons, probably something right about -18cc. Your compression ratio will naturally be higher with the extra 1/4" stroke in a 377, a lot higher (like 11:1) with a flat top. IMO 11:1 is only doable on pump gas with aluminum heads IF you go with a pretty big cam (like 290-295* ADV duration).

Don't know how many miles you have on your engine as it is, but if there is any significant wear on the cylinders it would probably be best to punch it out .030". If the engine is real fresh then you can probably break the glaze on the cylinders and go with a standard bore piston.

Standard bore stroker kits should be available, they just aren't typically listed in the catalogs because they probably sell more +.030 and +.040 kits. Even if you can't get a std kit you can piece one together for about the same price (maybe even cheaper).

PS. If you will be using the hot cam get the 5.7" rods. They can make a hair more TQ on the bottom end, if you go with a bigger cam and rev it significantly over 6,000 the 6" rod is definately the way to go.

I concur.....

Thanks for the replies. Here is what I have come up with in a preminary search. These prices are from the Summit catalog.

4340 forged crank 3.75" stroke for one piece seal is $675 Cast crank $285

Keith Black Hypereut pistons, 18cc D-dish pistons $251 for 3.75 crank

My engine has only 1700 miles on it, so I assume the std bore should be good to go. Of course I'd measure it before ordering pistons.

I would re-use the PM rods that I have.(They are 5.7, right??) I would consider re-using the rings and bearings, assuming all are in good order.

Opinions? Am I crazy? Will 27 more cubes be worth the effort( or the money?)or would you guys look for more power elsewhere?

There is no substitute for cubic inches. The extra cubes are more than worth the effort IMO. My 383 combo is a full second faster than the fastest 355 I've ever built - that's not to say there aren't fast 355 combos out there, just that a 383 is a darn good idea - especially in a street combo.

I'm not sure what length the PM rods are. I would get the engine all apart and measure them before ordering pistons. I think there are 5.85" PM rods - not sure what they use in the ZZ shortblock.

You can also order a Scat cast crank for a one piece seal block that has a 3.8" stroke - for 383ci with a standard bore. They're very strong cranks, and I bet the price is pretty good.

Thanks for that info. GM has has a 4340 steel 3.8 crank, but they want your first born male child for it.

The Scat Cast 9000 crank, for a one piece seal motor and 3.75" stroke runs for $279.99 at Herbert Performance.

I'm a little leery of a cast crank...the lit says they're good up to 500 HP....this motor, should be at least within shouting distance of that, and I'm inclined to go with forged. Overkill?

I would say yes. HP doesn't kill cranks, RPM's do.

I've got a stock cast crank in my 412ci that puts out well over 500HP - it's a strip engine that's capable of low 11's, maybe even 10's. I make it live by keeping the RPMs under 6200.

Remember, the Scat cast crank is far superior to a stock cast crank.

Thanks, Matt.

While I have your ear...you seem to be the resident expert on the vortec heads. The way I understand things, the fastburn head is an improved version of the vortec head cast in aluminum. My question is: Would running the fastburn head with a dished piston have any negative impact on performance? I have seen it written that the fast burn combustion chamber was designed to work with a flat top piston. Thanks!

Al

deleted
oops, I thought we were talkin 385cid
But, the fastburns and any head/chamber will work better with a flat top.

Yes, the Fastburn/Vortec chamber will work better with flap top pistons, to keep the swirl going. This will allow you to run a slightly higher compression and still get away with pump gas. For example, I was running 9.6:1 static with a 266* (seat to seat) cam, and used 89 octane gas. That's not bad for an iron headed motor, and my dynamic was nearly 8:1. Combine that with using aluminum heads, you can get by with alot of compression.

Thanks again, Matt. Now the dilemma. Go with flat tops to keep the swirl, and risk too much CR as Eric said (11:1), or go with dished and ruin the design of the heads?

I'm guessing the hot cam as an advirtised intake duration around 270? Not really sure.

I don't think your compression will be too high to manage. Since you have a new block, your pistons are probably .020-.025" down the hole. Combine that with a .051 head gasket (used on ZZ motors), and assuming flat top pistons have 5cc valve notches, that makes your CR 10.4 with a dynamic of 8.2, which is kinda pushin' the envelope. Personally, I think 8.2:1 dynamic is possible with aluminum heads, fast burn chambers, and 92 octane. May have to play with the ignition timing a bit.

Here's what I would do: Remove heads and check how far down the pistons are at TDC. If it's .020" or more, use flat tops. If less than .015", go dished. If between .015 and .020, start adding up pros and cons of each path you can take.

Once again, thanks. Not to get totally off the subject, but isn't that quite a large quench area? (.051 + .025)?

BPOS,

I am running a 383 with fastburn heads, flat top pistons, 5.7 rods and a Comp Cams XE274 (230/236 @ .050). The car is at sea level, but on the other coast from you.

Pump 93 octane is right on the ragged edge for me. I throw in about 2 gallons of 103 just before I go to the gas station to top off with 93. My toy only gets about 2,000 miles a year put on it, so I don't mind dicky-dooing around with the gas. Of course, your mileage may vary.

Originally posted by BPOS:
Thanks again, Matt. Now the dilemma. Go with flat tops to keep the swirl, and risk too much CR as Eric said (11:1), or go with dished and ruin the design of the heads? Dished pistons will NOT hurt your power or quench. The old 70's smogger dish pistons are a thing of the past --- modern D cup pistons have a very effective quench area and make every bit as much power as a flat top, if not more.

PS. A quench height over .060" and below .100 is generally considered a BAD thing. Engines with deck heights in this range tend to produce "abnormal" combustion in the quench area. Shoot for .035 - .040" if possible --- the increased compression ratio is more than offset by the detonation reducing effect you create. There is some good reading on this subject in the KB catalog.

Thanks for all the replies. I think I have a fairly good handle on what I need to do, which is basically to disassemble the engine and figure out my deck height. Then it's a matter of selecting a piston/head gasket combo that puts me in the proper compression ratio range with the proper quench.

One final question: Since I will be able to manipulate final CR a bit, what do you guys think I should shoot for? (5.7 rods, aluminum heads) I will be using the Hot cam. Thanks!

PS Found this compression calculator. I'm sure many have have already seen it, but for those who haven't.....

http://www.angelfire.com/fl/procrastination/motor.html

Shoot for 9.5 - 10.0:1 on the compression if you stay with the hot cam.

Don't risk going over 10.0:1 because it will not buy you much HP anyway and you do not want to risk detonations problems - especially if you decide to run KB pistons.

A -18cc dish will put you at 9.6:1 with a .035" quench height.

Thanks, Eric. Sorry to drag this on and on, but the tech advice here is excellent (and free).

I guess I'm looking at Eagle and/or Scat as the main suppliers that match my wallet. Any preferences? Is mixing and matching OK? I like the looks and the price of the Scat Pro Series I Beam rods (I decided to forego the PM rods - the thought of grinding them scares the HELL out me). Eagle or Scat H-beam rods are a bit more$$ but are they any better? And the Eagle 4340 one piece rear seal crank. Yeas or nays? Thanks!

Al

Oh, didn't anyone tell you? TC is charging .50 a letter for advice . . . LOL

I know what you mean about the mix and match thing. I don't think there is a problem doing that except you will need to make sure everything will balance up OK. You might want to bounce specific part numbers off your local machine shop or whoever will do the balancing. You also want to make sure you get the right bearings for your crank - there are some that have a large radius on the journal and need the large radius bearings to match.

As for I Beam vs H Beam, IMO the Eagle or Scat I Beams are good to at least 500 HP. I have a 3 year old set of the Eagle SIR's that have survived many many 1/4 passes and even a broken piston. I think the fancy H Beams are more a peace-of-mind / marketing thing.

Just my opinion.

PS. there are some really good I Beams out there too - I think Crower Sportsmans are very good and reasonably priced too (about the same as the Eagle H beams I think)