TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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I got a question for anyone dealing with this cam.I have an 87 trans am 350,9.8 to 1,l-98 aluminum heads,afpr,hi flo runners,ported plenum,airfoil,stock base,ads strip chip,relocated mat,accel cap,wires,coil,rotor,slp 1 5/8 headers,3in ypipe,3in hi flo cat,3in. flowmaster catback,9 bolt with 3.27 gears,i figured on at least mid to low 13's with this setup the best ive ran was 14.10@97mph with great traction and a 2.01 sixty foot timeand no knocking or timing retard!!!I've gotten a lot of good advice about fuel pressure and possibly the injectors(22lbs./hr.)being to small to feed this combo.Has anyone experienced anything like this and what else could it be?Seems to fall on its face at midtrack could be lack of air because of the tpi or lack of fuel from small injectors or the prom is just totally wrong.Any suggestions would be big help.
I think he should still be low 13s with heads or not. If you look at his signature, you see he has stock 22#ers. Believe me, these are not nearly enough for that motor. I saw an L98 on a dyno 2 days go with a similar setup with blueprinted 22lb bosch's and he still wasn't getting enough. He's going with 30lbers, as should pete.
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91 Formula
305 TPI 5speed
1LE/G92/WS6
Paxton SN92 polished kit, SLP airfoil, ported/polished plenum, March pulleys, Crane AFPR(43psi),Crane Gold 1.6rrs,MSD coil,MSD6AL (5200rpm limit),Holley 9mm wires,Ac delco R43ts plugs,stock chip,Ford SVO 24# injectors,Bosch O2sensor,SLP 1 5/8" headers,SLP catback,shortened shifter,3:73s w/Auburn posi,170* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.
Thanks Form i believe this thing has got to be something so simple im gonna kick myself in the *** when i fix it.I've seen guys running 350 tpi stock with just regulators and catbacks doing low 14's and high 13's.Well time to go crank up the fp if you here a big boom from the nj area you know that wasn't it
I see in the sig that you have a stock intake. Even a ported stock base is gonna kill you on the higher RPM's, and that cam will fall flat on it's face. That cam starts
making good HP at 4500+ RPM's, peak torque starts in the high 3K range. A stock intake can't breathe up there...
22lb is plenty to run your setup. So says the math, so says TPIS, so says my LT4-HOT equipped 355 TPI running stock 22lb injectors at <80% duty cycle pulling 950mV on the O2 sensor.
Find a buddy w/ Diacom, get a scantool, or otherwise find a way to capture ALDL data while the engine is running and see what's going on in there. Read Tim Sifford's terrific article on software tuning and PROM burning. Take control of your engine and you'll be really happy.
I see several problems with your setup.I see 2 ways you can remedy this. The first and more expensive way,1.Youll need a looser torque coverter about 2600 stall and a shift kit(if you dont have one already).2.Port the heads3.definately ditch that crappy chip,and get a custom one made.4.get a larger base and 52mm throttlebody or I say if your going to keep that cam just move up to a MiniRam and 58mm.5.replace injectors with atleast 24lb ones6.upgrade fuel pump7.get larger 1 3/4 headers and highflow dual cats8.3.70 gears.9.modify MAS.I just dont like that cam for any longrunnered TPI setup.Its great for Stick LT1's and 4's but I feel there are several cams better for TPI's.It seems you have spent alot of money on parts already only to knock off about 5 tenths and maybe add 2mph,and the parts I suggested are even more $ but the second way could do this is1. change the cam out to a milder one (SLP 51002 is a good one)2.22-2400tc+shift kit3.port manifold/52mmthrottlebody,in4.Modify MAS5.custom prom.It wont give you as much power as the other setup,but it should still put you solidly in the mid to low 13's (with DR's)and will be much cheaper,but how fast do you want to go?
Whoever told you that you need 24lb injectors is smoking crack. With the stock 22lb injectors I was running 12.5's at 108mph with a 218/224 cam, AFR heads, and fully upgraded LTR intake. I only swapped to bigger injectors when I installed the MiniRam and was topping the RPMs at 6500. There is something else wrong with your setup. My first comment would be that your setup is 100% out of balance. You can't expect to run fast with an unbalanced setup. I see this so many times with the LT4 HOT cam. That cam was designed by GM for the LT4 which has awesome heads and very high flowing intake. Putting that cam in a basically stock L98 is equivalent to taking away lowend torque and not gaining upper RPM horsepower because your intake and heads don't work well with what that cam demands.
Shorterm solution: Upgrade your intake and install a 2800 stall converter. Mike Davis and Kevin91Z have been having luck with the aluminum L98 castings. However, you will need an upgraded intake and a higher stall converter.
If you haven't seen this dyno test yet then take a good look at it. A fully upgraded large tube runner setup will feed you motor up until about 4800 with the HOT cam and L98 aluminum heads. But, at 4800 it starts to fall. If the upgraded setup flows only to 4800 then I would imagine that your setup flows significantly lower. The HOT cam is designed for upper RPM horsepower and your intake is choking it. Furthermore, the HOT cam will cause you to lose some lowend torque and you'll need a higher stall converter (and possibly some 3.73's) to help you out.
Longterm solution: The above mods + real heads.
Tim
------------------ TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8) All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=- Moderator: PROM board at thirdgen.org
Of course it sucks, because its not the best cam for your combo. I'd have recommended the ZZ4 cam instead.
My LT4 HOT cam works great in my engine, but I have TPIS base/runners, TPIS 52mm TB, ported L98 heads, SLP 1 3/4" headers, and a flowmaster cat-back. You've got the runners, you need the intake manifold to go with them. I'll find out how well hopefully tomorrow at the track.
Thanks for your help guys!as far as low end grunt there is more with this cam then there was with the stock l-98 one.I am really not dissapointed with it down low just the last 1/8 mile where it just runs out of ooomph!from what ive read the Lt4 heads only flow abot25 cfm more than these heads plus the intake/exhaust ratio isn't as high as the l-98's.Reccomendations on an intake either the superram or miniram really dont want to go to high with peak hp plus i dont want to go to a 3.70 rear to get the engine to spin up that fast and high.im thinking the superram will give me the same tourqe but should extend the breathing capabilities by at leasr 1000 to 1500 plus its a little cheaper.is there any place that can burn me a chip for a reasonable price.dont want to spend a grand on the computer alone.
I have stock heads and only a ported plenum and the car runs great with my new LT4 HOT Cam, at least much faster than it did with the stock cam. I figure my ETs dropped by a good .4 or so.
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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End
Here is my opinion (for what it's worth)
TRAXION, I agree with you on the injectors. Stock injectors (in very bad shape) have got me to a best of 13.39 to date (but I'm positive that it can run better as is), so PETE's problem is somewhere else. Now, I don't necessarily agree with you TRAXION about the LT4 cam just not working with the L98 engine. I have a '88 GTA 350 with stock cast iron heads (except for springs) and a CompCam cam (230/236*, 510/520", 110* LSA) that is bigger than the LT4 Hot Cam and I can honestly tell you that the engine never lost any torque, and did gain a lot of power. The engine might be mismatched, but it shouldn't lose much torque, if any. I agree with R.O.B on the stock '87 intake ducting; those rectangular boxes are very restrictive; I would suggest upgrading to '88-89. PETE, is your MAF gutted? I would gutt it if I were you. Is your Catalytic converter clogged, fuel filter good, plugs and ignition, timing set properly? Make sure you have the timing right, the stock damper can fool you; mine had the outer ring slip and I could never get the timing right. Start with your fuel pressure at 44psi and run a couple of times and see what happens, raise it and see if it gets better. Your 60' are not horribly bad, but that car should do better. If you are spinning your tires too much, then there is the culprit; you'll never hit 13.5 or less. You can easily lose .5 sec or even a full second when your tires spin too much. Last but not least, what's the altitude where you run. Too high and your number won't be impressive at all.
Hope this helps a little
Rick
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'88 GTA 350 Full of Leprosy (rust)
Headers, catback, free mods, Xtreme energy cam, intake pieces and 2100 RPM TQ
13.39@102.50 MPH
1.90 Sec ----- Best 60FT
104.23 MPH -- Best Trap Speed
AIM HIGH!
Dynotuning time Pete. You have more than enough mods to be in low/mid 13 second territory. Trust me. The dyno will not lie. It will also tell you if your rich/lean . They use $10,000 diagnostic equipment along with a wideband 02. I still say your too lean at WOT but only a dyno will show that.
[This message has been edited by theformula (edited March 09, 2001).]
have you checked your fuel pressure during the runs? before spending any extra $$, find out if your fuel pressure is droping during a 1/4 mile run...if it is, get a new pump, from GM, out off 90-92 vette, I think they are 115$...
I'd say, replace the lower intake, and check all the simple stuff like fuel filters, etc...you'll be suprised how much a fouled spark plug will hurt performance, or a burnt wire...then look into parts compatability (and complexity). You should be running mid-13's right now. P.S. Ditch the chip, get a good custom one. Those chips are usually programmed for basically stock engines (yours, obviously, is not).
[This message has been edited by dhirocz (edited March 09, 2001).]
The intake ducting i'm using is the box type system however i was running an 88 setup before and didnt see much difference and that was with a homemade ramair setup.I'm Leaning towards a new intake it seems that like a few guys said it runs out of air just as the cam really wants to pull.Now here is the question i have some cash to spend what intake would most of you guys suggest?I have the slp runners and an arizona speed and marine completely ported plenumon there already.I know the superram would let me pull it to about 6000 rpms where the cam likes to run at and not kill low end tourqe.Would the smart money go on a new ported big mouth base,a quality chip,and a converter with a 2000 stall or go with the superram and new cam such as the accel cam that is part of a lingenfelter designed package?211 in.219 exhaust 112lsa with .504in.,.514ex.or go with slp and keep pretty much all the mods from one source(slp)
Hey Pete,
I just got my car running with the LT4 hot cam last nite. I'm still chasing some fuel problems, but I can tell you that it pulls to the 6k RPM area. I mention this because of what you mentioned in your last post. I'm running a highly ported plenum, stock TB, fully siamesed SLP runners, and a hogged out stock base. These are things you could do rather easily (if you have the time ). IF you decide to change torque converters, get something looser than 2k stall. I have a 2700 stall Vigalante now. (I also have a 2500-2700 Neal Racing TC I will give you a deal on ). Reprogramming the chip sounds like a must. Consider the Do-it-yourself approach. It's the only way to get it "right" without putting it on the dyno.
good luck
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Bob '89 Ram Air Formula 350 And until that time when death won't wait, let each man rage against his fate.(O'neill) My car's homepage
My Hot Cam is killer behind a carburated engine the 3000 converter and 3.73's helped some too...
Look at the ZZ430 which has the Hot cam, It really impresses me that such a drivable engine could make that power.
Its still can't compete with a good running LS1 though, think I need to spray it
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-Joseph
ASE Master Automobile Technician
Scoggin-Dickey Chevrolet
1967 Camaro (Vortec Heads, GM ZZ4 intake manifold, ZZ4 roller camshaft) 1992 Firebird (Weiler Vortec Heads, LT4 Hot Cam, GM ZZ4 Intake, Edelbrock 750, eventually will be Ram-Jet)
Throw a blaster coil and a MSD 6A on there. Also the HAl shocks and lakewood traction bars (which were broken at the time of the run) dropped .4 tenths for me.
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1988 IROC-Z L98
License Plate: STG KLR 1
Engine Mods:
Edlebrock TES Headers, Hypertech Chip, Flowmaster Muffler, Intake Airfoil, Removed MAF Screens, MSD-6A, MSD Blaster 2 GM Coil, bored .030 over, Other minor mods
Suspension Mods:
Lakewood Traction Action Lift Bars, Hal Rear Shocks
Trans Mods:
2,500 stall converter, Redline clutches,Heavy Duty Steels, Trans-Go reprograming kit , Heavy Duty 2-4 band, Corvette Servo, B&M Mega Shifter w/ Carbon Fiber Handle (looks sweet in a black car!)
ET: 13.833@99.30
"If you can put it on your car, its fair" Quote By Guido
Foundering Member of the Illinois Overkill Crew (IOC) www.mfba.org
). IF you decide to change torque converters, get something looser than 2k stall. I have a 2700 stall Vigalante now. (I also have a 2500-2700 Neal Racing TC I will give you a deal on 
). Reprogramming the chip sounds like a must. Consider the Do-it-yourself approach. It's the only way to get it "right" without putting it on the dyno.
, Heavy Duty 2-4 band, Corvette Servo, B&M Mega Shifter w/ Carbon Fiber Handle (looks sweet in a black car!)
