Orr89RocZ

iTrader: (20)

aight, today was the first saturday test n tune and i went

tonz of ppl showed up so i only got in 2 runs before i had to leave for work

temp was about 72 degrees or so, humidity about 38-41%, barometer at 28.1-27.99
there was a wind, slight quartering tail wind about 10-15mph at times it seemed but i'm not sure how fast it was. it was on and off, a gust here and there

this was kinda weird and totally surprising to me

heres how it went... i fixed a torque arm bushing mount that was bad and fixed my header exhaust leak...

first run i spun off the launch, didnt heat the tires up that much and hit the throttle too hard

2.068 60 foot
5.939 330 foot
9.148 1/8mile
79.34 mph!
11.96 1000
14.311 at 92.18

second run this time in the left lane ( i always ran in the right lane lol)

this launch i heated the tires somewhat more than i usually do...
walked into it, no spin but it seemed quick and hooked well
but... 60 was not too much better??? oh well not my best, still more in it for sure, cuz i hit 1.8's

2.017 60 foot
5.813 330 foot
8.995 1/8mile
80.09 mph!
11.773 1000
14.112 at 100.67 MPH!!!

but look at that trap speed? so i pick up 8mph with nothin else changed, i think i shifted second about 300rpms sooner and first about 300rpms sooner. thats about it. my speedo was about at 100mph when i crossed too and its usually close at that speed with the new gears.

could the wind do that? usually, my best traps come with my best 60 foots

with the old 2.77 gears, i went 13.89 at 96.6 with 1.895 60 foot
now my 60 dont change that much more and i blow thru 100mph with just a full exhaust L98? very surprising and weird. if wind didnt do that, then i picked up 4mph with a gear swap

i wish time would have permitted me to run again but unfortunately it didnt.

89IrocZ350TPI

So you are actually running faster with the old 2.77's,but picked up four mph with the 3.27's. Weird how your trap speed went up so much. So what gears do you like better?

AlkyIROC

8 mph is a huge jump with only a slight increase in ET. I'd go with the tail wind excuse on that one.

Comparing incremental times between the 2 runs, the second run was faster all the way down the track. The time it took to go from 60' to 330' etc increased at each point so the entire run was consistantly faster.

Orr89RocZ

iTrader: (20)

well the 8th mile, the car is running low end of 3rd crossing that line and its up to 79-80 mph now which is what i expected.

my consistancy sucks!! the launch is very tricky for me.

my first trip to the track netted 14.2 at 95.5mph and 14.019 at 96mph. 60's were no spin and 2.04 and 1.94 respectively

another day i ran a 14.14 at 92 mph with teh 2.77's and a 2.02 60 foot

the very next run was my best at 13.89 at 96.6mph with the 2.77s with a 1.89 60 foot.

now with the 3.27's i believe a similar thing happened but with roughly the same 60 foot. i believe the fact that i didnt spin on the second run helped the car pick up mph but didnt change ET. just the way it worked out i guess.
the 2-3 shift on the first run was at 5 grand as by the tranny and it was abit slower than usual. it delayed there for just a bit. my 100mph run was at 4700ish rpm and i shifted it and it went into gear fairly quickly like it should. so i think that helped abit

my car must be really finicky about the shift points. i know it shifts abit too high right now but thats where the tranny shifts (5K rpms) i wish i could shift it at 4600 rpms or so

the 3.27's always felt strong on the street in 2nd gear. alot better than the 2.77's. i guess the weather REALLy woke the TPI up. heat really effects TPI. my other runs were in hot weather

Orr89RocZ

iTrader: (20)

anyone else have any input on this?

i realize my car is very finicky about the launch. ET's stay pretty consistant low 14's if mediocre launch but trap speed changes alot depending on launch and somewhat on shiftpoints although most of my shifting on all my runs was about same range, 4500-5000rpms

who says autos are easy to drive. LOL not on street tires.. i reallly want to get some slicks to see what it will do.

and a stock L98 with just airbox mods and full exhaust trapping 100 with a 2800 stall converter? that also makes me wonder whats up. guess these cars in the right conditions are no joke. converter alone eats up some trap speed and i still put out 100

i'm happy with it as is, cuz its now 100mph trapping car if its for real which i think its pretty close to that. maybe 98 and 2mph for the wind effects IF it was gusting at that time.

89IrocZ350TPI

Slicks should get you into the 13's no problem.

Trevor86TA

Your launch had little to do with it. Your 1/8 mile trap speed is similar yet your 1/4 mile trap speeds are 8mph off. The big change was the horsepower pull at the top end. Its really too bad you couldn't have made another pass to back it up. When are you going out again?

83 Crossfire TA

iTrader: (2)

I hate to sound negative, but I’m betting that that was a bogus run… some bit of trash got blown across the lights or something at just the right time, since 8mph is an incredible change to make in only the second 1/8th. Either that or you’re the most inconsistent driver that I’ve seen in a long time.

I’ve trapped 99.89mph with nothing but a cold air and cat back in my ’87 L98 car…

Orr89RocZ

iTrader: (20)

well if i can, i would like to go back out this saturday but then again i doubt i will have the time.

i know my consistancy sucks but what are the odds that something got blown across the line? i was thinking that but ruled it out cuz there really wasnt anything on the track blowing around, no leaves or anything and i figured the odds are slim to none.

Trevor86TA

It would be hard for driver error to cause that much change at the top end without you knowing that something big changed.

Orr89RocZ

iTrader: (20)

all i know is my 2-3 shift changed abit and the car just pulled on thru. the shift was lower by 300rpms or so, and quicker. so i do believe that was mostly it but again, i dont know if that justifies the increase in trap.

that 92mph first run was not a good comparison. most of my runs have been 92-94ish mph before i hit one good run of 95-96.6 before with the 2.77's so in this case i think its the same thing.

comparing my best run ever with teh 2.77s with the best 3.27's shows this

1.895 60 to a 2.017 60' -----difference of .122
5.648 330' to a 5.813 330'----difference of .165
8.808 1/8 to a 8.995 1/8----difference of .187
mph is 77.18 compared to 80.09 mph
11.563 1000' to a 11.773-------difference of .210
13.895 1/4 to a 14.112---------difference of .217 seconds
96.6mph to a 100.67

so the car is accelerating well it seems. the .122 difference in 60 times ended up being .217 seconds in the 1/4 mile. so if i drop to 1.8's with the 3.27's it should hit similar times thru the 1/4

compare that 1/4 run of 13.89 to my run just before that run.
2.023 60
5.839 330
9.024 at 76.65 1/8
11.798 1000'
14.148 at 92.44

so i have alot to gain with different shifting and launch.

87_TA

Its the timers - I have complained about it alot, but it only seems to effect cars with longer nose. 4th gens and mustags have no problems, but all the 3rd gen guys I talk with complain the same. . If you tell Frank, he will tell you its your car.

Usually my 1/8 Mph is faster in the Right but 1/4 way higher in the left - Usually about 4-5 for me. Seems less since I have lowered car.
I think there is a small dip on left that makes nose trip light.

Orr89RocZ

iTrader: (20)

so ur thinking a dip or something set the traps off early? and spiked my mph? interesting

my car is low and the front air dam sits low. front shocks set light, so bumps move the nose alot

it was my first ever run in the left lane.

89IrocZ350TPI

Soooo many factors

Orr89RocZ

iTrader: (20)

i know and i am so frustrated with it LOL

i need to nail my launch and get some good back to back conistant runs for comparison.

i would HATE to think that going from 2.77's to 3.27's would SLOW me down! how can that be? 3.27's are just abit more gear and great for TPI powerband.

but i realize that its not slowing me down cuz i picked up 2-3 mph on my 1/8 mph!! so i know i'm accelerating alot faster down low.. just need to get the launch down to get my 13's. its just my trap speed is all over teh place. 92-96.6 mph lol

89IrocZ350TPI

I hear so many stories about strange times after swaping gears on TPI cars. TPI cars may actually like higher gearing to fit its powerband. Good gears for L98 cars are usually in the 3.23-3.42 range. I can not figure out why you went slower going from 2.77's to 3.27's. Usually at the track it is alot easier to spin off the line than it is on the streets. I am sure you are spining more with the 3.42's. You say it feels faster on the streets but is slower on the track. On the streets you can get a better hook up. Get some Drag Radials and then hit the track and see what happens.......That would only make sense I cant think of anything else.

87_TA

Talk with other thirdgens at PRP, alot of the see that same problem.

Maybe the L-is the correct lane? But there is deffinetly a difference for me btween lanes as well as others.

When my car trapped 108, it would also trap 108 at quaker city
but 103 in R-Lane.

Orr89RocZ

iTrader: (20)

well i trapped a best of 96.6 in the right lane and if thats the wrong lane then wow my car rides out LOL


funny thing is i never see any thirdgens out at the track.. one one other guy last weekend and it was his first runs there too

he was trapping 98mph with slp runners/accel base and custom chip with 30lb injectors. 373 gears he was hittin 4th by teh end of the 1/4 which is too much gear for TPI.

TunedPort 335

Last year my car trapped 8.371 @ 80.09mph in the 1/8, on a 1.743 sixty foot. Get some tires and run low-mid 13s

87_TA

Good job! Its gonna pick up for you.

If it does not rain this saturday, You can use my et streets for a pass if you like.

But being this is one of my last weekends to race, I am heading to MIR maryland or ATCO new jersey if weather is going to be good. But its looking very doubtful so far.
I am sure my car will probably break anyways and I will have to get it towed 5.5 hours either way.

Trevor86TA

Even with converter slippage he should have only been trapping at 5000rpm in 3rd gear. Where does the "wall" set in on a TPI car with runners/base?

Orr89RocZ

iTrader: (20)

yeah i'm definately looking forward to gettin back out this saturday. i'm pretty sure i'm gonna go home this weekend and race. i wont have to work so i can stay there all day

i appreciate the offer on the slicks! that be great. i might be interested in that if i dont cut any good 1.8 60 foots on the street tires.

i'm partial to the right lane since its all i ever known.. so i'm gonna try and remain in that lane and see what i can do.

like i said, 96.6 was with 2.77 gears without the LCA brackets

base/runners should pull to 5 grand. stock is more like 4400-4500rpms. but he has 30 lb injectors which is WAY too much. he has a chip for it tho but still. stock 22's would work cuz he has stock cam and heads

83 Crossfire TA

iTrader: (2)

Depending on your cam, heads and exhaust… the stock TPI setup runs out of breath somewhere a little over 5500rpm, the stock heads run out of breath at about 4600rpm. If you’re running out of breath before that you’ve got something else stopping it up.

Orr89RocZ

iTrader: (20)

wow over 5K rpms? thats seems way too high on stock TPI even with a decent cam. most graphs i seen drop off tremendously after 4500.

now aftermarket i can see pulling to 5500 maybe

83 Crossfire TA

iTrader: (2)

Take it or leave it... the airflow is there, I've seen it done...

87_TA

Maybe I read this wrong,
but it says "stock heads run out of breath at 4600"
(Unless you mean TPI with stock heads)
thats wrong.

As for the intake,runners you can raise powerband slightly basically by making the engine less effecient earlier or using a lot less cubes.
Or a great flowing head with close to equal runner volume to squeeze a little more from the intake.
But on a stock 350 TPI engine, the first restriction is the intake.

83 Crossfire TA

iTrader: (2)

No, wrong.

the stock intake flows about 30cfm more then the intake port on the stock heads... If you find >30 cfm, a modern chamber design and good exhaust under the stock intake a 350 will be happy to about 5500...

Orr89RocZ

iTrader: (20)

hmm very interesting

havent seen many aftermarket setups pulling past 5000rpms but remain flat enough to about 5500rpms which aint bad. still leaning towards HSR tho.

83 Crossfire TA

iTrader: (2)

That's fine, I'm converting a victor jr to efi mostly because it's less hassle then pulling the TPI appart every few months to replace a leaking fuel pressure regulator or the same hassle to mess with injectors...

87_TA

Negative man,
Find me a dyno chart - pull to 5500 yes, make power no!

Coming from someone who has installed a mini ram on a completly sock engine with exception of headers.

Guess what, went from shift @ 4800 to 5900, would easily pull to 6400 just not making as much power.
And if I recall a stock TPI intake with runners will only flow 182 cfm vs the 216 of the heads?
And your problem becomes friction, not size. you have 17" + of small runner area creating lots of velocity, and filling cylinders extremely, well until it becomes a mechanical disadvantage because the air can only move so fast.

83 Crossfire TA

iTrader: (2)

you've got the flow numbers reversed, the heads are in the 170-180 range (useable with the stock or stockish cam) and the intake assembled/complete is in the low 200 range.

87_TA

I will have to dig up some old tech articles when I have time.


Orr89,
Its looking like rain for this weekend - I think I am going to head to MIR for Sunday unless there is a change.

Orr89RocZ

iTrader: (20)

yeah rain out for sure

so i'm not gonna get a chance to go out

looking or nov 5 or 12

rjmcgee

This happened to my car in Portland OR this spring. Long story short, our club ran on the chassis dyno in the morning then went to the track that evening. I found out on the dyno that my tach was off and I was floating the valves at 5500 rpm. So at the track I have 4.10's and it was all set up to cross the line at something like 108 mph @ 6000 rpm. First run I float the valves a couple hundred feet before the finish line. So I shift into 5th and my slip shows 99 mph. Next run I just put in the clutch and coast across the line and I trap like 104. Ran close to 10 runs that night and if I shifted into 5th I trapped 99 - 100 mph and if I put in the clutch and coasted I got 104 -105 mph. Didn't make sence until I read this tonight.

Orr89RocZ

iTrader: (20)

i guess you shifting into 5th caused u to trip the first light beam early?

jimmy_mac

You've gotta do some porting to get any l98 heads aluminum or steel versions to anything over 200 cfm.

87_TA

Here,
Read this:
http://www.strokerengine.com/SBCHeadsFlow.html

882 Casting 204 @ .400 lift.

L98 Casting 198 @ .400 lift.

Some good info there.

It really does not matter though, and that was really not the dispute.
But its getting boring anyway.

83 Crossfire TA

iTrader: (2)

Dude, I’ve had it, you’re giving me a headache.

I though that you managed to find another source that has published yet another set of higher flow numbers for the L98 heads (these things seem to flow better stock as they get older, it’s a miraculous thing really…). The previous highest were the chevyhighperformance database numbers which are at least 10cfm higher mid lift and up then any other published numbers or any numbers that I’ve seen, which are about 174-178cfm at .400”. Turns out that you just can’t read (or possibly type) and they are just a copy of the CHP numbers, and actually list 186cfm at .400” (FWIW, .400 or even .300” numbers are really the ones to compare here since stock cams rarely go much over .400”, I’d be surprised if they spent more then about 25% of their open time at over .300”).

Now generally, for an accurate comparison you want to use values that you actually see for some time period, which would be maybe the .300” numbers (typically 148 to 160, 160cfm on the CHP database).

Assembled stock TPI… typically about 203 cfm (I think those were Bohanz’s numbers, I’ve seen as low as 198 and as high as 209), so unless you get rid of the stock springs, install an aftermarket cam… you’re easily 40cfm down in the heads then you are on the intake.

So doing some math, it looks like the intake is good for a peak of about 418hp, and the heads for about 325hp (at the crank, assuming the rest of the combination is fully optimized for a peak in that range).

Now the reason that it’s usually say something in the 30cfm range is that almost every iron version of an aluminum GM head has flowed slightly better.

Orr89RocZ

iTrader: (20)

whats the stock cams puttin out? i hear .415 lift on intake and .430 lift on exhaust. i thought L98's flow near lower 190's at .500 inch lift while the vette L98 flows 196 at .500? seems to be the numbers i have

math isnt everything. stock TPI may look good on paper to 400hp but i know no one with stock TPI pushing 400hp on crank. fully aftermarket tpi's are barely over 300 wheel. kinda dissappointing you know. i love the looks of the intake, just sucks it dont flow

87_TA

ORR89ROCZ - Sorry your thread got this..

Dude!
First off - I did not attack your character by making your little remarks as seen above nor do I appreciate it! If you can not make a valid point or provide facts don't turn to attacks.

You are posting BS man! You say that the TPI heads are the restriction and with good heads cam can make blah blah horsepower.. Then you say to make any HP with factory heads you must use big cam and good springs - well nooo ****!
Thats what you are doing with the intake!!
You use 90 lb seat springs and a cam that peaks at 200dur and 400 lift you won't make much power in any head.

We were not talking about making 400 hp with stock dur/lift , thats stupid - we were talking about getting the most from your heads as stock "casting".
Sure the mid lift flow is in 150-170 range, Guess what that is pretty repectable.. And above 400 lift, a decent mild cam say 500 lift 230 duration you are spending 60% of you time above 400 where those heads flow best!
But guess what your stock TPI intake,runners,plenum reach a terminal velocty in air speed due to small runner size and long length. Why do you think people siamese runners? To slow port velocty and take advantage of higher RPM HP!
Why do you think the 350 made peak power @ 4300 vs 4800 of the 305, not the heads. The long small runners were produced to make great seat of the pant feel (Great torque) and snappy throttle reponse while still producing good emmisions and
driveabilty since the were unable to make the HP at the time and be smog happy. If that intake is so unresctrictive, why do you suppose that the LT1's went to a short 3" runner?

To get 425 out of stock Minifold,Runners and intake you will need big cubes and probably still a cam with alot of overlap to use exhaust velocity to pull intake charge in.

Stop being a desk top dyno racer and read the facts, or try a race track.. I know lots of poeple that make huge hp at home

Oh here check out this web page - Its trick flows - I do not think they would inflate the L98 heads HP abilitys when they are trying to steal its market. 425 HP

http://www.trickflow.com/articles/dy..._body_wlft.htm


"Conclusion So how did our dyno duel end? As Superflow results show, the L98s peaked at 420 horsepower at 5,500 rpm, with torque maxing out at 440 foot-pounds at 4,000 rpm. While the L98s made marginally more power under four grand, the 23 Degree's better port design and bigger valves left the GM heads in the dust from 4,500 rpm on up. The Trick Flow heads kept pulling through 6,000 rpm, where they peaked at 460 horsepower. Torque maxed out at 451 foot-pounds at 5,000 rpm."

83 Crossfire TA

iTrader: (2)

Oh man…

To start with, most of the 305 heads used in the 80’s flowed similar numbers or better then the L98 heads (at least in the range of valve lifts that they were actually used at), even with the smaller valves, and even if they flowed the same with 45cubes less the same port will support the more rpm just like the same manifold runner will. At best you have no point here.

Second, in discussing what is the restriction with the stock parts and you’re now telling me to compare non stock heads (valve spring, guide, seal, retainer/keeper and then add an aftermarket cam and probably roller rockers) to compare it to a STOCK TPI intake. The screwed up thing is that even if you do all that, THEY STILL FLOW LESS THEN THE STOCK INTAKE.

And before you argue that they flow that stock, yes, they do, but the stock valvetrain won’t tolerate something more then about .480” lift and you’d have to get into the mid .5xx range or higher to take advantage of the .500” numbers.

GM design went to the opposite extreme with the LT1, going from tuned length runners for what they thought people wanted in a performance application (remember, this was designed in the very early 80’s, when 245 hp and boatloads of torque was WAY better then anything else around, and still gave a relatively efficient combination that solved emissions problems), to a totally untuned intake on the LT1. I’m no big fan of the L98, I think that the LT1 is a better design all the way around, and the non tuned intake is a more appropriate design for most applications. The place where the LT1 fell down was that there wasn’t enough plenum volume or runner taper to really take advantage of it’s benefits in a performance application.

As far as personal attacks, I was just stating facts, you read or typed the numbers wrong. PERIOD. That’s not a personal attack, that’s a statement of fact, your facts were wrong based on the source you cited for those facts.

Now you have made personal attacks against me, not stating any facts, and honestly I don’t care, you’re just making yourself look worse. I’ll just tell you that I’ve had years that I’ve made more dragstrip passes in one year then I’d guess that 99% of the board members ever have and ever will in their lives.

87_TA

Hmm, you make personal attacks stated above - I don't, and I am making myself look bad? Ahhhhh, OK
The arguement was stock castings - period.

Last I checked valves seals have little effect on performance. So you got me on that one

Please, post a dyne of a STOCK TPI intake, runners, plenum and making 425 stock and you will be proven. Less than that you are reaching...

Sorry, adding a cam does not changes the factory head castings..

And its just common sense that you change springs with it. The fact here is you make a false statement and are changing things to try and validate yourself. I have posted links to dyno graphs, flow numbers and lots more. You have given nothing "period" except for turn to personal attacks when all else failed.

This has gotten so stupid: You like the stock TPI, I like the stock heads.. does it really matter anymore?

Orr89RocZ

iTrader: (20)

lets leave it at stock heads and stock cam and stock TPI sucks...

not bad if your looking at 350hp or less for a daily driver

but serious ppl play above those numbers, and that requires new intake, new heads, and new cam

you guys are presenting some good info, but this has been discussed before in many threads LOL

i dont mind the discussion in here because my question to my car and situation at the track has been answered.

87TPI350KID

TPI is nowhere near the best racing intake.. but you can make it work and still have an awesome DD. Someone on here, I forgot has some hogged out SLPs and a trick intake that makes some serious power running in the high 12s