Say I had a bone stock IROC with an L98. If I replaced the TPI stuff with an L69 carb/intake/aircleaner would it be faster or slower?

 

slower.

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92 Pontiac Firebird Formula WS6 5.7/A4
K&N, Blue Streak Cap and Rotor, strange unknown exhaust system (sounds good though)...
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slower. if you put the carb from that set-up on it. man..why in gods name would you ever switch to carb? from TPI??? tpi can really rock with some time and a dremel or die grinder and get 25mpg! i know because i did the switch, it isnt a great idea.

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89 firebird formula


360 10:1compression (350 .060 over)/fully balnced and blueprinted
comp cams xe262 cam
performer rpm intake/port matched to heads
#1405edlebrock 600
sportsman 2 heads 64cc 2.02/1.60 valves 200cc intake runner/cnc pocket ported
msd 6al/msd8.5 super condutor wires
h.e.i. proform 50,000 volt vac. advance ditributor
700r-4 with 3.08 first gear and 3.73 7 5/8 rear end.
b trans shift kit(will kill shifts...suck dong!!)
shorty heddman hedders with custom 3" pipe y-pipe back(no damn cat!) with 40 series flowmaster!
griffin daul1" core rad.cutom fabrication to fit(but no cutting )


future mods: 406 roller REALLY REALLY REALLY RADICAL!!!!!.with lots of NOS

 

I really, really doubt it would be slower.

Assuming one took the take to make sure the Qjet was in good condition, checked the secondary rods, made sure the Air Valve opens all the way, and swapped the computer system in properly, it shouldn't have any trouble making a little more HP and a little less TQ than the car did with the TPI on it.

Those of you who are saying it would be slower, why? You don't seem to have any reason besides the fact that the L69 was slower than the L98. I'll give you a hint... that fact had very little to do with the L69's induction system which is good well into the 13s if properly taken care of.

 

I also doubt that it would make you slower. If you were to put a larger cam, and get a better gear it would really help out. I also cant see why one would compare a L69 (305) to a L98 (350). The 350 is probably much more restricted by the intake setup. I havent done the swap so you may want to take the advise of people who have, but it seems fishy to me that it would make the car slower.

 

Hmmm.... I have a 305 (that's a 305, no typo) in my car right now with the stock L69 carb and intake on it, and all emissions devices installed and operating, such that it passes California emissions. Now I'm not saying it's a stock L69 engine, it just has the stock (that would be absolutely, completely, original, unmodified in any way except for minor tuning, just like it came on my car in 83... you know, that kind of stock, not like what the M*****g people call stock) carb, intake, and air cleaner. This engine does approximately 260-265 crank HP according to a chassis dyno, which measured 214 RW HP.

Correct me if I'm wrong, but I don't know of any L98s that put out 265 HP with the stock induction system on them. I feel fairly certain that if this induction were on a 350 instead of a 305, that 350 would put out more than 265 HP; probably closer to 300.

Draw your own conclusions about faster or slower. My bet would be that it would be about the same speed, faster if anything, but gas mileage would go down slightly and emissions up slightly, assuming that it was properly tuned to the engine once it had been installed.

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"So many Mustangs, so little time..."
ICON Motorsports

 

absolutly it would make more power, they didnt put FI on becuase it made more power then a carb it was for emmissions. a carb healthy cam and good intake can make a world of diffrence in power. 98% of drag cars are running carbs for a reason,....

 

Hmm...you haven't been doing much reading obviously. If you did, you would notice EFI is kicking the snot out of carbs as far as performance. A proper EFI setup against a proper carb with identical engines will make more power. Look at the ramjet engines, they are proof in the bag that EFI is king of the hill. Oh yeah, and the ramjet lineup wasn't designed for emissions or gas milage...performance WITH an added bonus of gas milage.
EFI systems can more accuratly adjust air fuel ratios and when you can do that you have the advantage. Carbs are great for simplicity but they aren't the future. Saying that 98% of drag cars are carb is a worthless fact. EFI is still expensive, THAT is the reason why carbs are still at the track.

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, Jon (350 TBI!)
91 Red My website

 

A bone stock TPI on a 350 isn't a proper EFI.

 

YEA !



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1986 Iroc 305 small block chevy: ported heads, 1 3/4 slp headers, rpm intake(ported), 1.6 roller rockers, performance valvejob, titanium retainers, compcams conical valvesprings looking for cam.

 

I'm down watching the cars run at the Dragstip generally once a week from march till november, I generally pick up on a trend or two down there.

Unfortunatley the Factory type EFI cars have yet to make anything more than a ripple in the fast lanes, or in the competition.
Every tuesday night they run a gambler's race, The only EFI cars I see that make waves, are Fuel injected, alchy blown rails.
In that capacity EFI's worth it.
99% of the cars in the gambler's races and points series races that make it to the final rounds are, Carb powered, Auto, and mostly chevy powered, or, EFI,blown, alchyrails... the only stock parts found on them is the key to the daily driver on the pilot's key ring.

 

I agree with J Prevost. A carb is easy to work with, but they can't compare to a good fuel injected setup.

 

Geez... carb bashers anonymous.

Anyways, the L69 in 1985 was (under)rated at 190hp, and the LB9 was rated at 210hp. The FI car ran slightly faster than the carbed car, but nothing to write home about. (Car+Driver, October 1984: Tested a L69 Manual tranny car with 3.73, and LB9 auto car 3.42, both optioned the same, the L69 ran a 15.4@90, the LB9 ran a 15.2@91. You can twirl your finger in the air now. They also tested Neil Bonnet's IROC, and managed a pathetic 13.6@107 although supposedly the motor was only putting out 413hp.)

Seeing as how the TPI is sorta restrictive on a 305, I'd venture to guess on a stock engine its either gonna run the same or a little quicker if in fact the TPI is as restrictive as it seems to be. If you are looking for some sort of major difference, I dont think you are gonna find it no matter which you choose.