Hey everyone I have changed my plans for my L98 road race engine build. I have decided to build a bulletproof 355 or at least a stronger than stock 355.....my question is if I wanted to go with a nice crank and decent rods with an emphasis on weight savings what am I gonna be looking at as far as my budget goes....i'd like to keep this as a budget build. Also does anyone know the power limits of my stock L98 1989 rods and crank? thanks BTW my power goal is 300-350 wheel hp and a projected redline of 6500 rpm I will be ditching the TPI as well in favor of a miniram

 

Id toss the parts in the trash for regular 6700 rpm bursts.
In 89 the rods got a little wimpier. GOod for low rpm torque motor but not what you want...
You have a pm

 

6700 is a lot of rpm, especially for your hp goals. I would recommend either buying a longblock from a reputable source, or if cost is the most important factor building a motor yourself as close to their specs as possible. Golen has some pretty good options, and the gm performance crate engines are pretty good also.

 

When I built my road race L-98 I took a different tack. I built a torque monster 355 that I shifted at 5800 rpm. Engine had 400HP at 4800 rpm and 500 ft lb of torque at 4000 rpm. With a ZF-6, changing gears brought the torque to the peak torque rpm at each shift. The car would fly and was bullet proof.

Stock bottom end except forged pistons
Blue printed
AFR 190 heads 2.05 inlet, 1.6 exhaust
Lingenfelter 74219 cam
1.6 RR's
Accel SR
52mm TB
TPIS headers
MSD 6A ignition
Mallory rev limiting tach w/6000 rpm chip (shift light set at 4800 rpm. According to Diacom by the time I shifted, engine was at 5800rpm)
Dyno burned chip
AFPR
McCleod dual disk clutch w/ aluminum flywheel
Lots of development time.

Speed Merchant in San Jose built the engine.

My $.02

Good luck.

Larry

 

Larry, I love the idea and it sounds like the engine was a torque monster which is what you want on a road course anyway! did the stock rotating assembly survive long with those numbers?

 

I have exactly what you are trying to build. 354rwhp@6050rpm with a 6500rpm rev chip, use 6700rpm sometimes but it's not much of a difference. By the way, my torque curve is flat enough to sit a cup on.

1990 2 bolt block .040 over with ARP main studs
speed-pro forged .040 pistons
eagle 5140 I beam rods
scat cast steel 3.48 crank
comp cams XR276 hyd roller on 114lsa
Pro-action 180cc heads with 987 springs
TPIS miniram with 24lb ford injectors
52mm TB
10:6-1 compression
headman 1-5/8" long tubes

Here's what i would change if i did this build myself. ditch the 987 springs for 26918 springs, also ditch the XR 276 in favor of using it's 230deg exhaust lobe on both the intake and exhaust, bring the LSA to 112 you will not pass emissions if you do this BTW. those changes should be good for at least 15 more hp which would be 370rwhp out of 357ci motor. that's mustang rwhp too by the way. you could also use AFR eliminator heads since they flow almost identical to the pro actions. go with whatever is cheaper, they are both great and stomp every other 180cc head on the market. Also, the scat i beam 4340 rods are stronger and not much more money, may be worth the piece of mind to use them. the eagles are beyond good enough at this power level but the scats are stronger. you might get weights on both before you make your choice. also the cast steel cranks are plenty strong, the only drawback is they are harder to clearance than their forged counterparts. you can't quite get as tight of run out on a cast crank.

 

Are those heads iron or alum?

 

 

Aluminum, flow peaks at 262@.500 with great mid and low lift numbers, exhaust was around 210@.500 can't remember the exact number. Basic 3 angle job with ferra valves and a bowl clean up is all that has been done to hit those numbers. not bad for a little 180

 

I had no problem with bottom end because I kept RPM under 6000. I also had a big 26 row oil cooler and a 2" radiator for those hot Buttonwillow days.

Larry

 

what pistons did you use?