Alright guys, this is more of a thinking out load, looking for opinions post more than anything else.

Right now I have a 1990 L98. I bought it cheap with a bad motor, had a Jasper short block put in using Federal H423NP pistons (hyper, http://www.summitracing.com/parts/SLP-H423NP). Block is .040 over, giving me 357ci.

Now, I have a slight knock, only in neutral with the clutch out. I'm thinking its the flywheel or something similiar (but thats another thread with sound to determine that).

My basic goal is not so much a HP figure, but I'd like to run high to mid 11's with the right combination, while still maintaining good streetability and driveability. I also want to do this not on a super budget build, but with budget in mind.

I built the car when I was 17-18, and unfortunately hindsight sucks, but I went cheaper rather than doing it right the first time and spending the extra money back then. Now I'm wondering if I made the right choice. I know the crank is a cast recon'd stock (or stock replacement), but have no clue what the rods are. Block is a 4-bolt main.

A few questions I've been kicking around:

1.) Are these pistons good for around 450hp?

2.) I figure going to a 383 would cost close to 2500 dollars extra vs just doing a heads/cam/intake swap. Figuring on a block, plus costs to bore, hone, deck, clean and check, forged internals (would do it right this time) and labor would bring it to about that. Now, lets assume I match a good set of heads with a cam and changed the L98 to a modded HSR or MR or the likes, what would the hp difference be between having a good 383 combo vs my 357 combo?

I'm trying to decide if that 2500 is worth it, or if I might only see 30hp with the difference displacement.

My goal is not to have the fastest drag car. I would just like a streetable car that can keep up with a C5Z (what I was thinking of selling my C4 for, before I realized it was the least economical option for me).

So anyone with bored 350's that can give me ideas and ET's and HP for their combos, and same with the 383 guys? That'd be greatly appreciated. I'm leaning toward an AFR/Comp cam/ HSR combo and thinking that would work well and might not be that far off from a 383 with similar top ends.

P.S.- Some more info. This motor ran 13.2@101 (I think, I forget the exact trap speed, but the time is right) at Cecil on a spring night. 60 foot time was horrible as I still had cheap tires on it (2.2 seconds). So I'm looking to shave 1.5 seconds off that.

Current mods are in my sig.

 

ive never found h/c combos to give you what you think they would.
making those changes plus the extra torque everywhere from a little extra stroke yes!

save longer and build the bigger motor everytime.

knock is probably your fw setup

 

If you like to rev it, and depending on mileage since build, staying with a 350 crank will work. Nice start with 4:11 gears though you didn't say if you have a hood mod to house an HSR.

I have a 383 conversion and feel it was worth every penny. 30hp difference doesn't tell the whole story. More importantly, if you really build for higher revs and a strong spinner, you'll be pulling it apart anyway.

I too, think your knock is the FW.

 

Well, I think the 383 would stand up to the 357 depending on what ammo you use. And since a .44 will blow a mans head clean off, the 383 is a goner.



Sorry I am feeling froggy this morning.......on to the next serious reply

 

You should be fine as long as you keep it under 6500 rpms which will limit hp potential abit but still should be enough to run 11s

How heavy is your car? There are quite a few heads/cam stock shortblock L98 fbody's running high 11's or atleast near that with good trap speed. Its doable and can keep it driveable.

HSR or miniram is a good idea and really is needed for EITHER motor IMO. TPI just isnt worth the time for your goals.

I had the same goals as you with my old 383. Keep up with or beat C5Z's all motor and keep up or beat C6Z06's with spray. I did just that. 11.4's at 118-119 which is bolt on C5Z performance, and 10.6's at 128 on spray which is C6 Z06 typical performance with bolt ons well driven or even mild cam setups.

It was AFR 195 with ported HSR intake + custom grind hyd roller by Bret Bauer. 230/245 .603/.613 109 lsa. Wicked sounding but very driveable. All forged internals. Not really cheap but done right.

If you wanted that 357 to go 11's, It will need to spin alittle higher than your typical 383 to make same power. Bigger cam needed usually.

Given 2 motors, 357 vs 383 and same heads/cam/intake used on both, the 383 will make similar hp maybe abit more but at a lower rpm level than the 357. However the area under the curve thru the low end and midrange will be in favor of the 383 with its long stroke. Thats well worth it.

Your goals are easier to do with 383 but can be done with what you have. AFR 195's or Pro-filer 195's would be my choice for heads. Then cam like 280XFI or 282HR with 1.6 rockers. I like to see a 110-112 lsa at the widest but the xfi 113 will be smoother at idle. I tuned a mild .060 over replacement shortblock L98 with old school AFR 190 heads and HSR in a 3400-ish lb Fbody. 280XFI cam. Had good lopey idle but stable enough to daily summer drive. It is a bit racey for a 350 motor but works very well. His problem was not enough valve spring to control the pretty aggressive cam lobes and it floated at 5700 rpm. AFR 8019 spring upgrade on the new 195's will handle the cam and are a $100 adder that I strongly recommend. Even with his valve float the car was running 12.2's at 112 with only 330whp by 5700. Cam wants to go to 6200+, shift by 6500 so perfect for stock shortblock and would have made 350-360whp on his setup. Easily high 11's in good weather. With newer AFR 195's it would be 380-390's whp as some guys have made those numbers on stock L98 shortblocks with HSR/AFR heads.

 

355 superram, 219 cam, 10.5 cr, trickflow 195 heads, 2500 stall, drag radials, 3.07 gears, headers, 11.81 at 114 mph full weight, very streetable.

 

Ideally I'd like to shift around 6k.

I realize that the 383's main benefit the torque from the longer stroke throughout the powerband (especially the lower RPMS). My only real concern is if that extra torque lower is worth basically doubling my time and expenses to do it (I figure 3.5-4 grand for the top end, 6.5-7 grand if I do a forged stroked 383). I'm not sure it's worth it. Then again, I never drove a 383 car before.

Nice. Has it been dyno'd? Nice to see superram/smaller cams making decent times.

 

Heres the thing... your comparing a fully built/forged bottom 383 to a basic mild cast rebuilt 357.... the possible combos you can run on these motors will be different based on the parts you use. One is limited on rpm due to cast assembly and one has basically unlimited potential. Obviously the built 383 is gonna make this much easier to do and can exceed your goals but is more expensive...but built to last a while. Tough call to make.

383 torque is worth it IMO especially when your talking about the cost of a cast crank over building the basic cast crank 350's like you have and your shooting for a fairly quick 11's sec street car...its little investment for big gains in lb-ft and keeping rpm range down to be safe on internals. Plus theres more potential in power with more cubes, just need to feed it. For instance, 224 deg cam in a 355 may peak near 5800-6000 rpm with a 195cc head. In a 383 it will peak at 5500-5600 with same head. HP's would be close at peak but like I said before, the 383 torque will be up every where. Power under the curve will rule for a street car.
With the 383, the potential for making more power comes from being able to cam up abit larger to run the same rpms as the smaller 355. To get the 383 to peak at 5800-6000, it will take about a 230 deg cam. Now you have a larger cam in a larger motor turning same rpms, that is more hp/tq every time. More cubes need more head and cam to run a certain rpm range.

Keeping the cast bottom end to 6K would be safe but now your limiting power potential. Need a smaller cam to keep hp curve down to allow for 6K shift point. 383 will allow you to put in a bit larger cam than the 357 and thus make more power.

Now when you talk about doing a 383 with fully forged built bottom end, then hats off, sky's the limit. You can turn as much rpm as you want as long as the parts you choose are built for it and balanced to the rpm. If you have these parts and "doing it right the first time", might as well built it up to take advantage of its potential. Give it some 210cc heads and a 236-240 deg hyd roller and turn near 7K shifts. It be a wild street car and do low low 11's. Do a flat top piston and 11 to 1 compression with 64cc chambers. Will live on 93 oct with the cam being over 230 deg duration and abit of overlap from a tighter LSA.

If your options are a rpm limited cast bottom 357 trying for 11's or a fully forged/built 383 for the same goal, you will crush the goal with the 383 and be worry free about the motor breaking down. 357 is cheaper since you have it

 

Quote:
Originally Posted by bjankuski
355 superram, 219 cam, 10.5 cr, trickflow 195 heads, 2500 stall, drag radials, 3.07 gears, headers, 11.81 at 114 mph full weight, very streetable.

Nice. Has it been dyno'd? Nice to see superram/smaller cams making decent times.

It dynoed at 342 RWHP at 5700 RPM and approx 400 RWTQ at 4700 RPM. I shifted at 6000 RPM and the car was very streetable. I still have this engine in my Firebird and it has 100,000 miles on it and still runs great. This is a all stock bottom end engine except for hyper pistons, (In other words the same set-up you are running).

FYI, I ran the exact combination of parts on a 406 and it dynoed at 357 RWHP at 5250 RPM and 437 RWTQ at 4000 RPM and that combination on average ran 3 tenth faster in the 1/4 mile in similar conditions.

 

This post makes the most sense of all the other posts Ive read on this thread.

 

Good to see guys like bjanski and SurfnSun pipe in on this
Not too many here track or dyno their cars before after.

There will be another before/after track time-Superram thread coming up soon stay tuned.

 

Understood. My main concern is even though the block is about 7 years old, I only have 10k on the motor. Sure if I did a fully forged 383 it would knock the socks off my cast/hyper 357. My main thing is how much more I'd get out of the car vs. the price I would be paying.

I think I'm going to go with heads/cam/intake for now. It's cheaper and should tide me over for a few years.

So, doing some reseach, I was thinking of going with:

-AFR 195 heads
-Comp 268XFI (218/224 durantion .57/.565" lift) or Crane HR284 cam (222/230 duration .509/.528" lift) style
-Stealth ram or miniram (like the longer runners on the stealth ram, but like that I wouldn't need to modify a miniram to fit under the hood).

Now, is that a good cam duration range I should be at if I plan on shifting around 6200? Stealth ram or miniram (lets say both cost the same and are as easy to install)? Would the shorter runners be a hinderance or won't there be as much difference?

 

Yep both cams are good for that rpm range. Should be a mid 350-370whp car or so. XFI cam would be stronger with more lift and if it was on a tighter 110-111 lsa or so. Still idle good too. But crane cam is a proven cam just its been around a while and has mild lift.

 

I think those XFI cams are in the 113-114 range for LSA. Supposed to be friendlier for FI idle. (Of course, you can custom order a cam with any LSA, duration, or ICL)

IMO, his selection "could" come down to mild versus aggressive lift. One (as you point out) will put more power under the curve -- meaning more torque from idle to redline. The other will be easier on springs. Considering the low mileage use (which was finally posted), the more aggressive XFI cam would help keep some torque...and really not give up anything in the hp department.

If he could get that HSR under there, you get more torque still. Anyone who's seen back-to-back dynos for the HSR vs MR (like the 10-times-the-Torque comparison), you know the HSR provides a bit more torque until about 6k rpms. If not, consider a superram or FIRST intake for better torque. Either will make it feel more like a stroker.

To make the 357 as fun as possible (in lieu of a stroker), with the low mileage on the existing build, and with an expectancy of low future mileage, I don't see why the XFI cam wouldn't be the better choice. Plus, the AFR 195's can "use" that extra lift w/o having air stall issues.

Even with a 383, I'd still say to shoot for at least .450 lift. Those AFR heads will let it in, and higher rpms will definitely benefit from it.

 

I think I wouldn't mind modifying a HSR.

However, I remember looking at FIRST before, but not having much on them. Is there anywhere recent I can check out some build logs or at least see some HSR/FIRST comparisons?