84 cross fire
Pro
Joined: Jan 2003
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From: newark DE
regardless... stock vs stock... mod vs mod... TPI wins everytime over CFI
Le Mans Master
Joined: Oct 2003
Posts: 6,130
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From: seattle WA
Well, I think his point "stock vs stock" is valid, and you can't say porting is stock. But what's the point, both (C4s) are to restricted to compete against most...and the key word is most stock performance cars off the floor today, including some lowly 4 bangers. That is "stock vs stock".
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Well, I think Paul did say a stock TPI vs a stock CFI that the TPI would win (Post #8). Now, as far as 84 CFI vs 85 TPI stockers, all things being equal would probably come down to the best driver. However, I do believe that later yrs. 86+ stock TPI with aluminum heads (stock) all else being equal the TPI would come out ahead...of course the driver is a big factor. But equal drivers...my moneys on the TPI.
Last edited by rick lambert; Nov 14, 2007 at 07:13 PM.
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
Just my 2 cents.
It would all come down to the driver like Rick and Tom said.
84 205hp stock motor 290 ft lbs tq, 85-86 230 hp stock @ 330 ft lbs.
According to R&T (not me)tests in a quarter mile using automatics there is a differance of up to 1.3 seconds in the quarter. Thats enough time for either driver to make enough mistakes to allow the other win.
My wife's 84 is stock and I have no experience on a track...
Anyone with a stock 85,86 with the same experience thats wants to test this?
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
If you're going to try to compare box-stock CFI's vs. TPI's, then '84 to '85 is the ony test worth talkng about. After all, the whole "argument" was about intake system potential.
If you start talking about later model 'Vettes than '85 then the "TPI" intake system is benefiting from more and more improvements -other than the intake system itself, and is a worthless comparison. To take my point further, saying that a box stock TPI is better than CFI and using a '91 250 hp (6 speed) TPI 'Vette as your TPI example is dumb. Comparing box-stock intakes '84-'85 is reasonable since the only change was the intake system, ECM and pistons.
Clearly, having runners that are approximately the same cross section as the head ports, the '85 TPI (Box-stock) will out perform the (box-stock) choked down 2/3 port sized CFI intake system. Once you grind out the CFI runners to match the TPI runner size, it's a wash.
If you start talking about later model 'Vettes than '85 then the "TPI" intake system is benefiting from more and more improvements -other than the intake system itself, and is a worthless comparison. To take my point further, saying that a box stock TPI is better than CFI and using a '91 250 hp (6 speed) TPI 'Vette as your TPI example is dumb. Comparing box-stock intakes '84-'85 is reasonable since the only change was the intake system, ECM and pistons.
Clearly, having runners that are approximately the same cross section as the head ports, the '85 TPI (Box-stock) will out perform the (box-stock) choked down 2/3 port sized CFI intake system. Once you grind out the CFI runners to match the TPI runner size, it's a wash.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Except more than just a wash. The '85 uses the same pistons as the '84. The only difference in the 1984 and the 1985 long blocks is the camshaft. So the '85 has the better fuel distribution of the superior TPI system and a faster, more sophisticated computer. However, if the Crossfire manifold had the same size (cross section) ports as the 1985 TPI base manifold, GM would have had problems selling the TPI. Believe it or don't.
RACE ON!!!
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Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
In case you never noticed, an LT4 doesn't use a TPI manifold. Maybe not in that race, but my car ran a 13.37 @ 104.65 on street tires.
As CFI-EFI has said, if you've ever looked at a CFI manifold, the ports are 2/3 the size of the head port. Think somebody was holding something back there maybe?
The point is that some of us had fun correcting the "mistakes" the General made with CFI.
Mistakes like crap fuel distribution (2 different size injectors), lazy cam, lazier ECM, and a choked intake manifold. And then scaring the p*ss out of LT motor cars like yours.
Last edited by Dominic Sorresso; Nov 14, 2007 at 09:57 PM.
Burning Brakes
Joined: Feb 2006
Posts: 1,098
Likes: 1
From: Webster Texas
I read an article a few years ago that GM had a "mule" CFI car that was making 255hp net, at the same time the TPI was starting development, they had other emissions and similar requirements to meet that denutted the L83 and the first L98's. But a 255hp CFI car in 84 woulda been something!
Pro
Joined: Jan 2003
Posts: 515
Likes: 3
From: newark DE
In case you never noticed, an LT4 doesn't use a TPI manifold.
Maybe not in that race, but my car ran a 13.37 @ 104.65 on street tires
Maybe not in that race, but my car ran a 13.37 @ 104.65 on street tires
As CFI-EFI has said, if you've ever looked at a CFI manifold, the ports are 2/3 the size of the head port. Think somebody was holding something back there maybe?
Mistakes like crap fuel distribution (2 different size injectors), lazy cam, lazier ECM, and a choked intake manifold. And then scaring the p*ss out of LT motor cars like yours.
the point i was trying to make was that, while your times for a Xfire car are impressive, theyre nowhere near what a good running LT4 would produce. after reading your post, someone who doesnt know much about these cars might believe that to be otherwise, and would have effectively digested wrong information
The point is that some of us had fun correcting the "mistakes" the General made with CFI.
Last edited by tpivette; Nov 15, 2007 at 01:09 AM.
Pro
Joined: Jan 2003
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From: newark DE
how is the 84' cheaper to mod than TPI? the only real difference is the intake... things like headers, gears, tires, cams, heads, are all the same cost for either an 84' or an 85'. and who said you cant port a TPI intake just like you can a Xfire? there are people who have siamesed their TPI base manifolds and have gotten the motors to make power well above the "wall" limitation
Le Mans Master
Joined: Oct 2003
Posts: 6,130
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From: seattle WA
Well since we're down to comparing 84 CFI to 85 TPI lets see, both were 9.0:1 compression, both were Iron heads, I don't have the specs on the cam so I can't compare, and I doubt the ECM added any HP. But the 84 made 205 BHP at 4300 RPMs and the 85 made 230 BHP at 4000 RPMs....equal drivers and it seems to me the 85 wins hands down. Incidently you may as well throw in 86 iron heads as well...same as an 85...230 at 4000 RPMs, GM changed to 9.5:1 compression on the aluminum heads starting with the 86 vert, and HP jumped to 240 at 4000 RPMs same for the 87,88 and 89.
So if I'm making 230 HP at 4000 RPMs and it takes you 4300 RPMs to make 205....that should be the end of the story....every thing else being equal. Stock 85 TPI should kick tail on a stock 84 CFI. Wasn't that the whole discussion?
So if I'm making 230 HP at 4000 RPMs and it takes you 4300 RPMs to make 205....that should be the end of the story....every thing else being equal. Stock 85 TPI should kick tail on a stock 84 CFI. Wasn't that the whole discussion?
Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
I love when people compare times from different parts of the country. There are a lot of factors involved. What may run a 14 in one situation can easily knock down a 13 somewhere else. Maybe that 104 Sopresso wasnt in as a favorable air/track condition as your 107. Maybe he would have stayed with you...or not.
Does it really matter?
Does it really matter?
Pro
Joined: Jan 2003
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From: newark DE
maybe, maybe not... but the LT1s mph really wasnt the point... merely a comparison to say if a stock LT1 could trap 107 (which was higher than his modded crossfire) then there could be no way that he shouldve taken the stronger LT4, had the driver been up to par
again, alls i was trying to say is that the comments made and the accompaning video are going to mislead Xfire owners into thinking they can knock off LT4s all day long with only a mid 13 sec car that traps 104mph. yes his modded 84' did in fact beat the granny shifting 96', but thats the one instance where it happened, and its certainly not the norm. with the drivers being equal, the Xfire should have been walked bad
again, alls i was trying to say is that the comments made and the accompaning video are going to mislead Xfire owners into thinking they can knock off LT4s all day long with only a mid 13 sec car that traps 104mph. yes his modded 84' did in fact beat the granny shifting 96', but thats the one instance where it happened, and its certainly not the norm. with the drivers being equal, the Xfire should have been walked bad
Last edited by tpivette; Nov 15, 2007 at 03:40 AM.
Pro
Joined: Jan 2003
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From: newark DE
most TPI cars came with either 2.59s or 3.07s. if you have a stick, then i think the ratios could be either 3.07s or 3.31s. i dont think it was until the ZF6 was released that the 3.45s were availible
Pro
Joined: Jan 2003
Posts: 515
Likes: 3
From: newark DE
Just my 2 cents.
It would all come down to the driver like Rick and Tom said.
84 205hp stock motor 290 ft lbs tq, 85-86 230 hp stock @ 330 ft lbs.
According to R&T (not me)tests in a quarter mile using automatics there is a differance of up to 1.3 seconds in the quarter. Thats enough time for either driver to make enough mistakes to allow the other win.
My wife's 84 is stock and I have no experience on a track...
Anyone with a stock 85,86 with the same experience thats wants to test this?
when i do aquire one, im going to do the whole bolton thing with dyno and track verification. i actually wouldve rather done a full bolton Xfire to see what they can do as i dont really know of anyone who has gone this route. however, i know of a few TPI guys that have done this, and at least 2 have knocked off 12.4s at 108mph. but since those were "newer" TPI cars (an 89' and a 91'... both autos), i guess their times wouldnt be valid according to you guys
sooo, anyone living in the DE/PA/NJ/MD area wanna try an stock vs stock, modded vs modded, CFI vs TPI challenge? im looking to pick one or the other up after the holidays
Last edited by tpivette; Nov 15, 2007 at 04:08 AM.
Drifting
Joined: Feb 2004
Posts: 1,277
Likes: 1
From: Santa Maria CA
I owned a 87 prior to my 84 and I did track results before and after. I wasn't a member on this forum when I had my first vette ( 87 ).
1987 auto 3.07's paper filter but flowmaster cat back ran 14.441@97mph
1984 auto 3.07's K&N fitler stock cat back ran 14.889@91.03mph
1987 auto 3.07's paper filter but flowmaster cat back ran 14.441@97mph
1984 auto 3.07's K&N fitler stock cat back ran 14.889@91.03mph