Well, I finaly got the wife's approval to do an engine next year (please, no comments on my lack of manly authority in the household :D ). I'm starting to plan out the build and would greatly appreciate input / opinions from you guys.
I have a '96 LT4. It sees road-racing and street use. I'm not a drag racer. I also am not concerned with huge HP or torque peak numbers (of course more is usually better). I'm looking to build a motor that can wind out to 7000RPM if needed, but still have a pretty flat torque curve. Don't care if it has a rough idle. Emmissions are not a concern. I don't need a huge amount of torque -- a wide powerband is more important to me (for road-racing). Endurance is also very important. I'll probably have the machining and assembly done at Fast Times Motorworks (same shop Monty uses).

Here are the parts that I'm already planning on using (comments welcome):
- 4-bolt LT block (wanted a 2-bolt to do splayed caps, but got a good deal on this one)
- LT4 heads / intake (porting to be determined)
- oil cooler
- High-capacity oil pan
- 52mm or 58mm Throttlebody (depending on what configuration I end up with)
- Cold-air induction
- 6-speed with 3.73 gears
- crane Gold 1.60 roller rockers, 7/16" studs, guideplates
- Stock ignition and reprogrammed stock computer
- 6 Inch Oliver forged rods
- Cola forged crank
- 1-3/4" Long tubes, probably Hooker
- Callies billit main caps
- JE/SRP forged pistons
- Total Seal Rings
- ARP Main and head studs

Questions:
1)I'm currently leaning toward building a 357 (4.03" bore, 3.5" stroke) I know I'll need a good forged crank. I know it's not much more to build a 383 or 396, but I prefer the revving ability with a shorter stroke. I'd basically be trading torque for slower piston speed and more revving ability. Opinions?
2)Heads, trying to determine where to get them ported. I know I can get a little more out of AFR's, but I already have a spare set of LT4 castings. I'm currently considering CNC Heads or More Performance. Anyone have any recommendations? I plan to go with 2.02/1.60 valves.
3) Cam. I'd prefer to stick with a hydrolic roller to avoid adjusting lash all the time. Possibly a rev-kit to help at higher RPM. Anyone have opinions on this vs. solid roller? I figure I'll work with Fast Times to pick the specific profile once the engine configuration is finalized.
4) Water pump. I'd like to go with a Mizerre electric pump so I can get rid of the cam-drive pump. However, I'm concerned about reliability in an endurance application.
5) Injectors: keep the stock 26#ers, or 30#? I guess this really depends on question #1
6) do I need to worry about a fuel pump?

Sorry for the lengthy post, but I really appreciate any input. Thanks!!!!

EDIT: Oops -- forgot to add that I have a 13# aluminum flywheel and lightweight aluminum ATI balancer.

[Modified by MarkBychowski, 1:04 PM 7/16/2002]


[Modified by MarkBychowski, 4:14 PM 7/16/2002]

 

The Valve problem adjusment is a myth. This last check i did was 4000 miles and nothing changed. 18+K miles on .600 + lift and the springs are all within a few pounds of what they were when I installed them. Modern Allen locking nuts and a stud girdles lock everything in place. At first after my breakin I had my rev limiter set at 7600 with my 3.750 stroke. I have since set it at 7000 and hit it quite often.

I just can't say enough good things about stroker motors. I had a hot 355 solid roller before. Strokers just seem to make so much more power than just the 30 or so cubic inch difference. It's no problem making them into 500 hp and 500 lbs of torque for 3500+ rpm wide.

Your 6 speed with 3.73 is never going to see red line in 6th gear anyway. I'm never going to see red line with 4.11 rear gears with a .70 top gear either.

The big thing to remember while building it is light weight motor parts. I have a 6 1/4 fluid damper, 40 pound light weight internally balanced crank, and light weight JE SRP pistons for 6 inch rods. In an under 600 hp motor I would get sub 600 gram 6 inch bushed rods. Like the Olivers you refer too. 3.600 3.750 3.800 3.875 strokers are much better options than 3.5 or less.

Instead of something air limited (that is, anything less than a miniram) I think you can't beat single plane manifolds with 1000 -1300 cfm EFI conversions on top of an solid roller 383 - 396 ci.

If you coming out of a turn going up a long up hill straight. There are only two things that are going to get you to the next turn faster. More FT lbs of torque or a lighter weight car. So I did both!:)

 

Thanks for the feedback!! I'm really on the fence with going to a stroker, but if they're really that flexible, I guess I can't see a downside.

Any other input? Thanks!

 

First question i would have is what class are you wanting to compete in for road racing. This will help out some cause of class rules limiting engine ci and such i would think that would be a limit.

I personally would look at a 381-383 ci motor not a huge stroke but has some. Cams there is tons out there and it comes down to how nasty ya want to go. more cubes generally more torque :) The thing though you get into is if you have more torque will it throw off your straight line cause you have massive wheel spin :) all be it very cool

I would also throw some questions at Fasttimes Motorworks and see what they recomend for your motor ci, stroke etc..

The mezziere pump is nice but i wouldnt trust it for a road race app personally i just wouldnt want to trust an elctric pump over a mechanical on a long term basis now i know alot prob run the pumps day to day but i wouldnt. I do run one in my camaro but that is a race app and not daily driven, or for long periods any longer.
Steven

 

Thanks Steven,
I don't do competitive stuff -- just track days, some competition, but not through SCCA or any of the major sanctioning bodies, so I don't have to worry about rules. It's just for fun.
You've reinforced my fears on the Mezziere pump. It might just be to risky.