I just recently fired up my new engine with HSR. It's basically a 5.7 L98 with flat tops (9.5ish), 212/218 cam, fully ported 083's, headers, stock TB ect. I've been taking it easy during the break in but it seems very strong. My question is regarding injector sizes and tune. Currently I'm running the stock 21 lb injectors with an custom chip with a total of 34' advance. I have the adjustable Holley regulator and have set the pressure at 45 PSI. At 45 PSI I notice a bit of hesitation when the engine is cold but it runs great when warmed up. My previous dyno run netted 237 rwhp with the TPI. I'm hoping the current setup will make around 350 bhp or so.

1) Do you think my power estimate of 350-375 is realistic?
2) Will I be OK with the 21's or should I go bigger? I've searched and used the injector sizing formulas but it depends on the power I'm making. 21's are right on the edge but I'd like to use them if I can.
3) If I stay with the 21's what pressure should I start at?
4) What is the best way to "tune" the fuel pressure.

I live near a 1/8 mi track and have a G-tec meter but no access to scan tools and would like to get pretty close before I go to the dyno.

I would guess ~325 to 330FWP without a tune, I would look into a set of SVO 24lb. you will be maxing out those 22lb out pretty quick

what does fully ported 083's mean? do you even get 200/150 out of them? those heads are pretty much garbage as far as i know.

youll be fine with 21 lb injectors because those heads wont let enough air in the motor to need anything more then that.
its a fairly streetable cam tho.

my stealth ram with a bigger cam and garbage dart iron eagle 180 cc heads, with crappy headers on it mind you couldnt pull out more then 275 wheel horsepower

with those heads and a small cam i think youd be lucky to see 275 at the wheels, with better heads and the same cam you could easily pick up 50-75 hp
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lol reading that again, kinda funny really, youre expecting to go from 237 hp, to 350=375 hp, with the same stock heads, a mild cam and an intake.

the intake doesnt make you any power, the itnake just lets you make power until 6200 rpms, need a big cam and heads to make that kinda power in a 350

[QUOTE=19doug90;3510310]

with those heads and a small cam i think youd be lucky to see 275 at the wheels, with better heads and the same cam you could easily pick up 50-75 hp
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lol reading that again, kinda funny really, youre expecting to go from 237 hp, to 350=375 hp, with the same stock heads, a mild cam and an intake.

Let me clarify. I am hoping to reach 350 flywheel power, or about 300 rear wheel power.

As far as the head porting. The 237 rwhp was with unported heads. I have extensively worked the bowls and cumbustion chamber. Definatly not flowing like some good aftermarket heads but shouldn't they flow enough for 350 flywheel horse power?

i'm shootin for 270whp this weekend with bolt ons on my L98...stock heads/stock cam with 1.6 rockers and HSR. i went 12.95 at 103.8. my buddies formula LT1 went 100mph that day and put down 261ish whp i think it was. i made 246 and ran 13.58 at 98.xx in the heat first day out with no tune. now i have tune/underdrive pullies/1.6 rockers and ran hella faster haha. i think 260's is what i will get but 270 isnt too far out of this world i think

i think you could put down 275whp easy, especially with ported heads with that setup but change a few things

if you didnt already add fuel thru the maf tables, i think your setup needs more fuel. i ran stock injectors (which i thought were 22lbs, not 21) at 48psi for my L98. air fuel was abit rich but i since tuned that out. we'll find out this saturday.
also bring your timing in earlier. timing/spark table bring max timing in by 3600 rpms. should really wake up that car

i would honestly be surprised to see more then 240 hp, and a massive drop in torque due to the new intake.
mind you torque shouldnt be a big issue on that cam cause traction issues usually happen long before power matters, and you make low end horsepower with that cam/heads

then again i also have no concept of how you ran a 12.9 on that setup, but i think i also remember you saying somewhere else that youre cutting like 1.65 60's, which makes a big difference

My car dynoed at 299 hp/338 ft lbs (the dyno owner said it reads lower than most dynojets in town by 20+ hp in many cases and my dyno sheet stops at 5,600 when we ran to the 6,400 rpm shift light, so the numbers could be skewed a bit low since it appears that the dyno tach could be off).

My combination is:

1992 Z28 M6 with 3.73's.
1995 block
0 decked
splayed main caps (not that they make power, but the line bore will help square things up)
ZZ3 forged crank
Lunati street race rods
KB Signature series 12cc dished pistons (.020 over, torque plate honed)
Speed pro plasma moly rings (file fit)
ZZ3/ZZ4 heads with Manley race flo (undercut) valves
K-motion K750 springs
Comp Pro Magnum roller rockers (1.52 ratio - 7/16 studs)
HSR
52mm throttle body
under drive pulleys with no air pump and no ac
Crane 220/230 .510/.510 on a 114 degree
Compression is about 10.6 to 1 (the heads were cut slightly)
SLP 1 3/4 headers (and it was dyno'd with a 2 on the left cat back, that's been replaced by a magnaflow race muffler that dumps in front of the axle)
24 lb injectors

I think that's all the important stuff. The rotating assembly was balanced and the harmonic damper is a Fluidamper "Streetdamper".

i cut a 1.70 as my best but my 12.9 runs were 1.710 and 1.72 60 foots car has good midrange. dyno'd 246whp with stock tune has to be 20whp more now

ya i guess stock heads are good for a little more then i figured.

dont know if youll pick up 20 hp with a tune, you shouldnt need that much more fuel in the engine over stock, but heres hoping, should definitly help pickup some midrange.

those numbers are encouraging tho, i made 275/315 with garbage exhaust and nothing resembling a real tune, and an electrical problem.
my only goal for the motor the way its setup now (long tubes, tuning it myself now and electrical problems fixed) is a 12.99 at the track. Course its finally ready to go and its winter now, might as well be at least

tune made a little difference...it wasnt so much the fuel as the timing mods i've made. saw about a tenth there or so.

also added 1.6 rockers and underdrive pullies and smog delete so those may have given me some power

point is, stock TPI is weak for stock motors. HSR or superam or even aftermarket TPI stuff should flow more than enough air to max out stock heads. you should see good gains there. Add a cam and port the heads abit and you'll see more power with a intake gain.

i thought these cars were very limited by stock heads but so far i'm impressed with how my car is handling these mods. i think 260whp would be impressive for stock heads/cam.

agreed, as said earlier wouldnt have thought youd get more then 240 out of it
which even then wouldnt have been that bad at the wheels, considering its only rated 245 flywheel from the factory

Yea I'd like 300+ RWHP, maybe too optimistic. 260+ seems obtainable. It pull much stronger than before.

The chip I have has the spark in at 3000 for 34' total/8' initial. The fuel curves were leaned out slightly. It's a custom chip burned to my previous specs but not "tuned" to conditions. I believe it's a good starting point. The only changes made since the 237 RWHP dyno run are;

1) HSR with adjustable reg. (already seeping fuel from the adjustment screw!?!)
2) Ported 083 heads with under cut 1.94/1.5's.
3) 1.6 rockers
4) Shim gasket and .010 cut on heads. About 9.5 SCR.

Currently running 46 PSI on fuel pressure. (Idle fluctuates more at 50 PSI) The engine really likes 4000+ RPM. Smooth and strong til about 6200 then it drops off and hits a wall at 6500. I don't think it's valve float- probably fuel or detonation retard, but I don't know without a way to get info from the computer. I think my next project will be at least data logging. Any good suggestions there?

stock cam right? it might feel like its pulling hard till 6200, but guaranteed youre not making any useable power over 5200 rpms.

that cam is specifically designed NOT to make power over 4500 rpms

EDIT, you dont have a stock cam, that cam will make peak power at around 5500 rpms, 224/230 cam in my motor ont he dyno peaked right at 6. I think those heads will flow 270 hp with that cam, which is embarassing because 275hp was all i got out of the dart iron eagles. Mind you i only bought those because i found out onr ebuild some idiot put 305 heads on my 350

stock cam on my motor peaked at 5050 before the tune. i hope its making power to 5100-5200 as thats where the trans shifts, but we'll see

i can see your cam peaking 5200-5300 or so. i wouldnt shift much higher than 5500


and get rid of that pressure regulator and get a new Kirban unit. if its seeping fuel already its gonna go out very soon. it could cost you power by not holding pressure at high rpms

BTW the RPM figures I gave are with the stock dash tach. I think it reads 3-500 RPM high. So shifting at 6k is really like 5500-5700. Seems to pull strong to about there.

And yes... the Kirban reg is next on my hardware list. Does anyone know what the cost is?

What's a cost effective way to data log?

Also, the 237RWHP dyno run from before peaked at 4500 with the TPI and same cam.

the Kirban AFPR is somewhere like $119.00 or something like that. I can remember.

http://www.moates.net/product_info.p...roducts_id=127

80 bucks plus shipping, and you need a laptop
need to download a couple files off the net to get the computer to read it, but those are free

that doesnt allow you to adjust your tune at all, just read the aldl port

Thanks for all your input. I ran my car this weekend at the local 1/8mi and it picked up a tenth with the HSR and 5 speed. 8.74 @ 80 best and 8.8's all day long. Previous best with TPI and auto was 8.85 with high 8.9's typical. Bumped the initial timing up to 10' for a total of 38' with my chip. Fuel pressure ended up at 47 PSI. Had a little problem launching though. This track has so much rubber on it that traction was NO problem. Well... unless you consider that my clutch went out after 10 runs! Best 60' was 1.9 with 2.0's typical. Just couldn't get it to launch hard. I had to let the clutch out at low rpm and let er rip. I think she'll pick up a little more when I get the new clutch installed. Hoping to get out of the hole a little better. It's kinda hard on the drivetrain with a full bodied car, 3.27 gear and traction. I'll keep you posted.

Hey another question. What fuel pump/system upgrades should I make? Currently running stock injectors but havn't done a tune yet. Figure I'm gonna need 24's or so. I still have a stock type (maybe the original) fuel pump and lines.

i'd do a tune first to see what the injector cycle duty is. I wouldnt think you would need more than 21-22 lbs for that motor although 24's would be safe bet.

I'd get it on a dyno and tune it. watch the a/f and see if its gettin any knock retard. adjust timing accordingly and see what happens. get teh air fuel to around 12.8 to 1 and see if your injectors are comfortable with that setup.

that cam is one step above stock and with the extra air from the HSR/Heads, i think the stock injectors will support power. its only going to 5500 rpms or so with that cam and shift by 5800 i'd say. 22's should cover that, especially if you keep pressure at 47-48psi at WOT.

because 22's are rated at 43.5 psi or so, and at 48, that makes 22's become 23's and thats close to 24's

24's will support near 380whp or so. your not near that and should be near 300whp

What do you mean by "comfortable"? Duty cycle between "X & Y"?

i think anything past around 75-80% duty cycle is too much

but you obviously dont want it super low either

yeah you want to keep cycle duty less than 80% from what i been seeing

I have a question. I'm considering buying a Stealth Ram for my 350 firebird. As far as I know it has stock heads and a stock cam. I do have headers and will soon have a 3 inch cat back kit as well as some upgrades to my ignition system. Would I really benefit from getting a stealth ram at this point or is my money best invested elsewhere for now? I was planning on doing new heads and a new cam next winter...

yeah i wouldnt waste my money on the intake, thatd be one of the last things id get. the HSR is expensive, and your not gonna notice much of a gain with stock heads and cam, its only when you get new heads/cam that you will benefit. Plus youll lose a lot of bottom end torque. I'd spend that money on exhaust, then heads and a cam, then intake.

Well lets take a look here....

i ran 13.63 at 97 with a 1.75 60 foot with my TPI L98. this was in november cool air. i estimate the DA to be in the 1500 ft range

with stealth ram and tune/pullies, no other changes, i went 13.2's at 101 on 1.74 60 foots. DA was about the same and this was in september with a unusual cold night spell.

1.6 rockers and a COLD winter day i went 12.95 at 103.8. 1.71 60 foot. DA was 188 ft. Damn near sealevel


HSR is a FINE choice even for a stock L98. i gained around 25whp, but moved that power band from 4200-4400 rpm peaks, to around 5000-5200 peaks. the difference was incredible. I still made 315wtq and it was table flat from 2500-4000 rpms.

I wouldnt buy into the loss of low end. its not that big of a deal. I have 2800 stall so naturally i dont feel any thing below that. But the loss wouldnt be that big over TPI since the gains above 3500 are just that good.

then with cam and heads, you'll have more options. I wouldnt waste time with TPI with cam and heads. Just leaving soo much on the table. might as well upgrade now and enjoy some power, because you'll have to upgrade when you do go cam and heads anyway

With the proper dynamic/static compression coming into play, along with the corresponding cam specifications, that torque can easily be brought right back....


-Gaspar

Hmmm... sounds like either way I'm going to end up bottlenecking something. Might as well get the deals while I can without messing with my total plan and it looks like the stealth ram might be my best option to start with soon as I'm done with my exhaust and ignition, which at this point is just a matter of getting around to buying the stuff I need. I also need to do more research on cam and head specs... don't know a whole lot about them yet. New to the game guys lol. Just got my car at the end of summer. Thanks for all your help.

Oh you will GAIN horsepower, that is true, I dont doubt that you gained that much horsepower. But you will lose torque, ive read a couple of dyno sheets on this already. But im saying htat for a stock motor, the horsepower/money ratio isnt practical throwing a hsr on a stock l98. Heads or a cam would produce more power for less money. HSR will show a bigger gain in hp with aftermrkt heads/cam.

yeah with a cam it could be brought back easily, but stock your gonna lose some, the TPI produces massive low end torque.

i'd like to see you do a cam and heads setup on a L98 for less than 600 bucks that i spent on my Stealth ram setup.

i picked up over 4 tenths and 4mph with just a intake manifold swap and tune for that manifold. Thats impressive for 600 bucks!! headers/catback is around same price and wont get you that gain. Not much will get you that performance.

The only thing that can rival that is a torque converter/gear swap for the price.

to put in a new cam, you will need headwork just to run the cam, and new springs/pushrods. Then you will need a tune for it. maybe lifters if yours are worn. timing chain, etc. simple 250 dollar new roller cam turns into much more expensive mod, plus its much more work

You seem to think low end torque is soo important. you may not make as much peak torque as a TPI setup, but you will make more midrange to higher rpm torque with the stealth ram over TPI and thats where it counts at the racetrack and on the street for performance driving. i still dyno'd 315 wtq. most TPI exhaust only cars will dyno 330 or so at the wheels. so i'll trade 15lbft for 25 more hp and loads more upper rpm torque with a table top torque curve any day. This is just my experience with it.

i think the biggest thing is as mentioned above, 350 ft lbs of torque is a bitch to hook on street tires. Even with my full bolt on lb9 5 speed car i can get the 255/50 3.08 posi rear to light right up from a 15-20 mph stomp, definetly hard from a dead stop to launch without much spin either, also thats with a set of pretty good falkenx ziex street tires n posi.

when i go ported heads and 2032 cam on the above combo i'm getting away from tpi myself, i mean i love the torque but, it's already almost useless down low, i cant imagine if i had 45 more cubes to play with better heads and bigger cam. Definetly can kiss streetable traction goodby. For sure i'd go with the more overall power with the longer usable powerband.

i suppose you add drag radials to this and you get a different outcome but, for a street car the upper end hp is nice.

not to really get off topic but i aggree, too much torque can be a problem. And every auto car should have a converter in it. even a small 2400. you wont notice the torque loss with a 2400 converter or higher.

OK, in regard to the torque loss with the HSR, I haven't "noticed" any with my setup. Check my sig. The 237 RWHP was with the TPI and before the head porting and Steath Ram. I run a 5 speed and 1st gear is pretty much worthless on the street. Full throttle at ANY RPM in 1st is tire smoke. It'll hook up in 2nd if I don't bang it. And the engine will still pulls well at 1500 RPM in 5th. I have not made a dyno run yet nor have I had this setup "tuned" but the big bad loss of low end just hasn't been a problem for me. If there is a torque loss on the dyno I would gladly trade low speed traction for the gains in the upper RPM's.

And that is the best part. The engine feels a lot stronger in the 4500-5500 RPM range. I'm looking forward to getting back on the dyno and dialing this in. For now I only picked up a couple of tenths in the 1/8 mile. Getting off the line with the 5 speed seems to be the biggest challenge so I would expect a greater gain in the 1/4 mile. And after a tune??? There is no way I would go back to the TPI now.

The most important aspect to me is getting a balanced combo. If I were staying with a 2.73 gear and stock stall auto I may stay with TPI but once I started making mods it was a bottleneck. If all you're planning is a manifold change then it may not be the best for a near stock combo. But if future mods are in your plan then the HSR is a good move. And let's face it, when you start going for horse power, enough is never enough!

If all you're planning is a manifold change then it may not be the best for a near stock combo. But if future mods are in your plan then the HSR is a good move. And let's face it, when you start going for horse power, enough is never enough!

^^ yeah thats exactly my point. im not saying you wont see a gain with the HSR cos u deff will, the tpi intake is restrictive.