2,000mi L98 355, 10:1
zz4 cam 208/221, .474/.510
8 degrees initial timing
stock heads
AS&M LTRs
stock ported base
ported plenum
700r4 shift kit, 2000 stall
3.27 rear gears
goodyear gsd3 245/50 16 all around
stock manifolds and exhaust- yes i know, they are killing me
here is how it went.
first run
60' 2.091
330 6.089
1/8 9.419
mph 73.76
1000 12.292
1/4 14.725
mph 93.19
traction on this run was awsome, i didn't feel any slippage, however my 60' isn't that good, i stalled it up a little higher on the second run but i lost any advantage with the exhaust. I think i could have had a decent 60' time launching harder with the exhaust connected.

for the second run i disconnected the i pipe after the cat, that gave the feel of less torque which is shown in the following 60' time, the .2 extra in the 60' explains the longer et.
60' 2.249
330 6.257
1/8 9.620
mph 73.33
1000 12.509
1/4 14.945
mph 92.66

Do you really think the exhaust is killing me that much? I mean 14.7 is slower than many stock L98 runs and the mph isn't too impressive either. Obviously that is from the TPI design. Oh this was at maple grove.
thanks guys
John

 

Ifeel your biggest problems other than the exhaust, would be the heads.i had a 355 with 204/214dur. and 450 lift cam,headers,3.73 gears,shift kit,msd,afpr,58mm holley,and stock heads and i only ran a 14.10. @97MPH. so get some heads and exhaust and youll see alot better times.

 

I once read on here,
"don't bother about taking in more air unless you can get it out just as well"

so I think your new LTR's, ported intake and the like will really shine once you get hedders and exhaust.

 

If you ever have those heads off for whatever reason..... spend some time and port them, even if you only do mild porting. The spots where the valve seats meet the guides are usually pretty bad (they have quite a ridge there). Clean up those intake ports too.

 

How much do you think mild porting would wake up those stock head cars?

 

Your heads and exhaust are killing you! Here is my own experience: summer of 2001 I was running 14.8's with a L98 and a 2.5" pipe into a flowmaster 80 series muffler. Winter of 2001/2002 I installed a set of Edelbrock shorty headers. I also ported the bowl's of my stock heads, the valve seats, 3*angle vale job, and plained them. Plus fresh valve stem oil seals. There was no intake or exhaust port work done. Summer of 2002 I ran 14.3 @ 98mph with ALOT of wheel spin. I have no doubt at all that with proper traction (Nitto's, and LCA's) I could have easily deeped into the 13's. Throw a torque converter on top of that and I would have been well into the 13's. And this would have been with a stock L98 with only slightly ported heads, headers, and exhaust.

Point being is imagine how much your stock heads and manifolds are holding you back with a bigger cam, larger runners, ported plenum and base, more cubic inches, and a higher compression ratio. PORT THOSE HEADS MAN!! You'll turn sleeping beauty into the beast!

 

Josh, do a search (l98 iron porting). Here's a good starting point https://www.thirdgen.org/techbb2/sho...8+iron+porting
This guy did a lot of work, but claims to get them flowing like a set of AFR's. So you can see the potential is there.

 

Yea, i know the exhaust is killing me, but 14.7@93? A stock L98 should be able to beat that. Oh well, i don't think anything is wrong with the motor, obviously exhaust is the next step. When i redid the motor i put better parts in b/c they really didn't cost more than stock replacements. And I scored the AS&M runners for $200 new, gotta love ebay. I just need to save up for exhaust now.
thanks guys

 

Your gears could also be killing you if you have the 2.73s. I went from 2.73s to 3.23s and i felt an immidiate differance. I have no track times to back this up yet but my previous best was a 15.6 with the 2.73s and i raced with the 3.23s and had to get on the brakes hard to not brake out and ran a 15.699. Gears might be your best friend to a low E.T.

 

ok nevermind i didnt see the whole post on your Mods.

 

I ran 14.2 bone stock in my 89 L98. I would seriously look around to see what you can find thats holding you back, problem wise. Get a scanner on there and see what its doing.

 

I'll post a log, maybe on the DIY prom board. I have a hookup to my laptop and i know a fair amount about the data but many are more knowledgable about it than i. However i didn't see anything wrong.

Perhaps a related problem. After the rebuild i fried my ecm so i got another 165 out of an s-10. Now it seems as though i have a speed limiter at around 110-115mph. The memcal and prom are the original for the car, just the ecm was changed. I thought the speed limiter stuff was in the prom but there is a definite difference. At around 115mph, acceleration pulses like a very slow rev limiter. Does anyone have any ideas? BTW it pulls stong to 115 and just stops there.
thanks
john

 

Not what you want to hear but I'm also using an S-10 ECM I found in the junkyard in my 383 car with no problems. You may have a problem somewhere else.

 

Interesting, that is what i was expecting to hear. Maybe the injectors are freaking out with extended high rpm. Or maybe a coil or ignition problem. Little problems always lead to a wild goose chases.

 

I'd say the chip is the problem. My car went 13.7 at 100mph when it was stock. Just a stall, air foil, home made air intake and cat back (NO headers). I didn't see what chip you have. I had the stock chip. It ran so good, i didn't get an after market chip.

 

Mine is a stock chip too. It is the original 350 chip. I guess it could have become damaged. But the car cruises nice, feels "good" just not quite as fast as i like. Thanks for the info. Tommrow I will check the ecm readings to see if i see anything strange.

 

Your gears could also be killing you if you have the 2.73s. I went from 2.73s to 3.23s and i felt an immidiate differance.

exactly!!! i went from 2.73 to 3.73. Boy did it peel like a *****. get some cheap shorty headers like hedman.

 

i have 3.27s

 

I have the log now, please let me know if you can look at it, i will email it to you. This was with the i-pipe didconnected. Will having the exhaust disconnected change results?

 

i have read all theposts but is the car tuned?.
also stock injectors? are u getting any codes?

or is thecar running really ruff and u think its cause the cam?(not trying to sound like an ***) but it hapened to me. i lost time from a cam swap, and never got teh car tuned. i lost 4 tenths from the stock cam.

this saying goes for anything in life. your only as stroing as your weakest link

right now there are the tune(maybe)
exhaust and those l98 heads

 

The obvious:
Your lucky if your stock heads don't stall out at 0.400" lift, and the ported base still could be a restriction...but neither is as much of a restriction as the stock exhaust manifolds and subsequent stock exhaust. You can do 13s by only doing exhaust mods on stock L98s.

Something else to consider is detonation. Your testing the limits of iron heads (especially stock ones). Do you know what your quench is? Too much advance can contrbute as well. Try using 93 octane, and a touch of 100 to see if improvements are made. The knock sensor may "hear" the loud exhaust that is bypassing the muffler and interpret it as detonation, and subsequently retarding your timing. With the added safety of some race fuel, you can disconnect your knock sensor. My knock sensor has been disconnected for a bout a year now with no ill effects.

Other thoughts:
Done a tune up lately? Changed Fuel filter? Fuel pressure holding steady at WOT? Is your posi still working?

EDIT: A computer chip will help considerably also.

 

i realize that replying to a post like this is just wild guessing since none of us can see the car or hear it run, but here is my take. i will agree that stock manifolds and y pipe do no favors, but i am running my stock 2.5 inch cat back right now and i honestly dont think it is hurting me much if at all. keep in mind LS1 cars are goin 12s with their stock 2.5 inch exhaust, so i doubt that the stock cat back is that much of a problem. as long as you arent detonating, i would maybe point to the use of the aftermarket runners and stock base, even tho it is ported. my buddy did this to his 87 GTA, he installed big runners with ported stock base and plenum and his car went slower. if the car runs good, and if all your readings from your laptop show that the computer is doing its job, i would guess that you just have a slightly mismatched intake combo.

 

Ok, good posi, the inlet of the base matches the outlet of the runners so i seriously doubt that is hurting me, yes stock tune, original injectors, 94 octane, no knocking, to my untrained eye it looks like the blms are a little lean, is anyone willing to look at a log, i will email it to you. The engine is only 2000 miles old. It has had all new tune up parts since then. Including fuel filter. I did get a code after all the racing was done. Code 36 burn off relay. I had the same code a few months ago and fixed it with a new burnoff relay, so i don't know whats up with it now. Perhaps that is doing it.

 

here is the data log, named 87iroclogfile

 

your car has allways been a 350 car correct, not a swapped in 350 car?

how does the car feel throw out teh whole rpm range 1k-5.5k?
i think isf u got a tune it would seriuosly help out your times. and i think you overcammed your motor.

 

Original 350 car, i don't think its that big. Many ppl go bigger with a stock tune. In reality its a small cam. Many use it with success on a stock prom. Anyway it feels 'good' very much like when it was stock. Of course it dies at around 5000rpm like all TPI's.

 

thats not th cams fault, its cause its a LTR setup

 

Yea, i know, its the nature of the beast. I'm not really complaining, i like torque. It pulls a better with the AS&M runners though.

 

i don't know many people runing on stock tunes, w/ a cam. but i mostly talk to 305 guys, 305s are much mor jumpy and pepy to mods

 

Yea, i would agree with out that that cam is big for a 305 but the 350 swallowed it fine. It idle fine, you can't really even tell it has a bigger cam.

 

https://www.thirdgen.org/techbb2/sho...ht=zz4+cam+tpi

https://www.thirdgen.org/techbb2/sho...ht=zz4+cam+tpi

https://www.thirdgen.org/techbb2/sho...ht=zz4+cam+tpi

https://www.thirdgen.org/techbb2/sho...ht=zz4+cam+tpi

I think your questions have been answered...match the combo. Maybe the above links will help.
The cam has more potential than the stock heads, intake (even ported), and stock exhaust, and stock chip will allow.

 

Those posts generally agree that the zz4 is feasible with a stock prom. This is why i choose the cam, i did my homework before built the engine, and i'm pretty confident the cam isn't hurting me, maybe not optimal but should be fine. Can anyone check out my datalog? as i think that will give an accurate reading as to how my setup is doing. And if the cam is doing funny things, i would think the datalog would tell us.

 

just because the intake base matches the outlet of your runners doesnt mean that you have a matched combo. the intake base is pretty crummy stock. i used a 6inch mandrel and really hogged mine out, then polished the inside of it with some cross buffs. also the outlet of the intake base is really small too. i did alot of cutting on my stock base to get it to match my aluminum heads. my point is, just because the port openings match doesnt mean the flow of the runners matches the flow of the base. the larger diameter runners will not have the flow velocity of the stock runners(given identical cams ect.) so the air has slowed down a bit and then goes into a stock base where it has to speed up. TPI is tuned length to creat intertial supercharging, when you start changing diameters and mismatching parts, TPI becomes useless. it is always a good idea that if you upgrade runners to step up to a larger base as well. your stock heads and exhaust manifolds dont do you any good, but they are not the limiting factor. many cars are faster than 14.7 and 93mph with stock heads and manifolds. do some more homework, ask guys like Vader, Willie, or Kevin91Z, they will tell you whats up.

 

For an automatic your 60' could use some work too. I don't see a torque arm in you mod list. a good high quality one from Spohn or BMR and maybe some lower controll arms could really help you 60' times. engine wise i would be dissapointed too. sounds like you need to first hook a scanner up and see what various modules and sensors are doing, then a cylinder balance test to make sure each injector is giving close to the same amount of fuel to each cylinder. maybe look into a set of blueprinted injectors....also what are you doing air intake wise one of the biggest problems is getting enough air in, with stock exhaust your not getting much out thats for sure, it must go both ways my friend.

 

I have a datalog posted about 7 posts up. All i am asking is someone knowledgeable in data logs to look at it. I dont' think it is some mechanical or mismatched components. I realize it is not optimal, but it has been proven over and over that runners with a stock (untouched) base will still net a few horse, so i'm pretty sure its not hurting me. I think there is something bigger going on. Like for some reason i seem to have a 115mpg speed limiter somehow. It never had and shouldn't have a speed limiter before the rebuild. Perhaps it is injectors maxing out. I have to go out check fuel pressure at WOT. To my untrained eye, looking at the log seems to make me think it is a little lean.

 

My car was running low 9.0s and high 8s in the 8th (1/4 mile times of solid low 14s) with stock heads and exhaust manifolds, and basically stock everything else...but 3" exhaust pipe...so I agree somewhat. But have you seen anyone running a ZZ4 through stock exhaust and stock iron heads on a 350!? I haven't...except this guy here... Usually the exhaust mods are done 1st, and rightly so. The people running good times in the links I posted previous are also using headers.

I believe his cam is not matched to the heads (at least lift wise)...(I don't think the intake matters too much in this case)...and not matched to the exhaust. I believe he would make a huge improvement with just headers and exhaust...In good tune, shouldn't have a problem running 13s. He doesn't have LS1 intake, heads, or exhaust, compression, etc....so I don't think you can compare.

I would like to see what the WOT fuel pressure readings are...and his injectors may need servicing.
I don't data log my own car, so I can't read others data logs...can't offer anything on that account.

 

Yea, like i said, i'm young and didn't have enough money to do it all the first time. Since i had the engine apart, why not put better parts in right? Its not like i don't want to do exhaust, i just didn't have the money. I think i'm about ready to do coated hooker 2055's and either edelbrock or hooker cat back. Anyway, i check fuel pressure. 38 psi with all the vacum lines hooked up at idle and coast. 44psi at WOT and somewhere inbetween for part throttle. Once i hit WOT fuel pressure is rock solid.

 

Originally posted by smithtc

The knock sensor may "hear" the loud exhaust that is bypassing the muffler and interpret it as detonation, and subsequently retarding your timing.

I wonder if this may be my problem. I have hedman lt headers with a custom built y pipe (no cat) the y pipe ends just before the rear end. I had the whole exhaust off when I was doing some work to the car and have not had the muffler put back on yet. It is pretty loud. I have taken it to the track a couple of times since installing a crane 2032 cam, the headers, and some other things, with less than expected results. When I drive the car on the street (at lower speeds) there is a noticeable power gain opposed to when it was stock. At the track my short times also improved but 1/4 mile times did not. It used to run 14.5 consistently, the best I have gotten so far with the mods is 14.0. Other runs ranged from 14.1 to 14.6. Is the knock sensor the one in the block on the passenger side?

 

For what its worth...I'm running 47psi at WOT on mine. I'd try experimenting with your fuel pressure. On one of the links I posted previous, the person set hie pressure on 50psi with good results IIRC using the stock ship.

Yes.