91 stock 1/4 mile - Chevy Impala SS Forum
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post #1 of 27 (permalink) Old 03-13-2003, 09:20 PM
pittbull
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does anyone know the stock 1/4 mile speed on the 91 caprice 350 with 3.42 rear gears 700r4 tranny the police package???????????
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post #2 of 27 (permalink) Old 03-13-2003, 09:41 PM
McThag
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A friend of mine's did 16.4 @ 83.

My dear discarded 305 did a 18.6 @ 72.
post #3 of 27 (permalink) Old 03-13-2003, 10:19 PM
pittbull
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cool kind discouraging though i added cam chip thermostat headers dual exuast no cats
1.6 roller rockers k&n filter deleted air pump redline 700r4 cherps the hell out 2nd
battery in trunk electric fans think i could break into 14's ?????
 
post #4 of 27 (permalink) Old 03-13-2003, 10:21 PM
pittbull
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oh yeah and does the 91 have a rev limiter?
post #5 of 27 (permalink) Old 03-14-2003, 12:24 AM
deanstud
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You might get into the 15s with that........Maybe
post #6 of 27 (permalink) Old 03-14-2003, 06:18 AM
kdrolt
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<BLOCKQUOTE>quote:</font><HR>Originally posted by willcaprice:
cool kind discouraging though i added cam chip thermostat headers dual exuast no cats
1.6 roller rockers k&n filter deleted air pump redline 700r4 cherps the hell out 2nd
battery in trunk electric fans think i could break into 14's ?????
<HR></BLOCKQUOTE>

You did all the right things, BUT...

1. what cam?

and most importantly of all,

2. what chip?

I have several thoughts. First, the chip is probably not well-adapted to the mods you made, so some tuning is really needed to wek up the engine.

Second, you didn't say what you've run at the track, nor what the full timeslip data was. You need to post that here.

Third -- you did a lot of mods (good choices!) but you didn't mention replacing the old tired fuel pump to a new one capable of supplying enough fuel to feed the engine. You also didn't mention changing the fuel filter.

Bascially, a stock 91-93 Caprice with the 9C1 350 can run mid to low 16s in the quarter mile. Slightly modified on the exhaust and revising the air filter, as has been done by several list members, you can run 15.5 to 15.8 sec.

You, on the other hand, changed just about everything.... so that suggests (to me) that you should probably be running 15.0 sec or better. So it would help us (or me) if you would provide the details of

1. what cam
2. what chip
3. full timeslip data + weather consitions when you ran

Lastly and IMO, you need to add a cold air intake; using a K&N in the stock filter housing is not really an improvement. This will help, but it's really not going to fix your problem. I think the biggest problem you have is with the chip and possibly with not enough fuel getting to the engine.

HTH.
post #7 of 27 (permalink) Old 03-14-2003, 10:37 AM
pittbull
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thats cause i aint ran it at the track and the chip is the thrmomaster chip from hypertech the cam is crane powermax cam
crn-104211 thats duratation I:194 E:204
cam lift I:407 and E:429 witch brought me to somthing like 428 and 458 at the valve
post #8 of 27 (permalink) Old 03-14-2003, 10:46 AM
PaulD
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IMHO, the biggest limiting factor on our engines is the fact we have only 2 65# injectors. They are going to deliver a maximum qty of fuel, regardless of how much air will go through the engine.

The stock L05 heads are not known for flowing well, but if you've already maxed out fuel flow a change won't do you any good.

My best ever is a 15.50 @ 87.xx. I've gone side-by-side with SS's and I can get a jump at the start, but I have to just watch them pass at the end of the track. Yea, it's definitely frustrating. I'm experimenting with the vacuum assisted regulator and a BB throttle body and injectors.

Now if I can only get some help making a chip to get it all working together.
post #9 of 27 (permalink) Old 03-14-2003, 11:54 AM
pittbull
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oh ya and yes it a new fuel pump but stock and filter gets changed way more than need 3 times in two years
post #10 of 27 (permalink) Old 03-14-2003, 12:02 PM
kdrolt
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<BLOCKQUOTE>quote:</font><HR>Originally posted by willcaprice:
... the chip is the Thermomaster chip from Hypertech the cam is Crane Powermax cam
crn-104211 thats durattion I:194 E:204
cam lift I:407 and E:429 which brought me to something like 428 and 458 at the valve
<HR></BLOCKQUOTE>

Ok that's helpful information.

The cam is better than a factory 94-96 Bcar cam, but not quite as good as an L98 cam... but it's still good enough.

Here's the problem. The cam is good enough to pump out 270+ hp if it were installed in a otherwise stock 94-96 Bcar LT1 engine (which has superb heads). You don't have those heads but you do have headers + duals, so your exhaust breathing is very good and probably better than the 94-96 LT1 has. So the 260-270 hp range is completely reasonable with that cam in your car.

But you aren't making that kind of power because the engine control (via the chip) and the fuel delivery are not enough to get close to those numbers.

OK taking the chip first: I don't think Hypertech does very much in that chip because it's a "one size, fits all" chip that, if I recall right, is really only going to alter the spark advance table and it will require you to use premium fuel. The chip might work well in a stock car -- but in your car, I think it will only make it run worse than the stock chip because the spark advance they use, plus the fact that your are probably running very lean, is a recipie for disaster.

Your mods to the engine, on the other hand, have greatly increased the engine breathing... so that means you need a lot more fuel to (a) prevent going lean and pinging, and (b) to actually make a lot more power than stock.

My suggestions:

1. Remove the Hypertech chip, and replace it with the stock one. If it runs better, then sell the Hypertech chip on EBay.

2. I assume you have a 9C1 Caprice, so that means you have the large 65 lb/hour injectors. That's good but it's not really enough. I don't think they will be able to supply enough fuel at wide-open-throttle, and they'll limit the engine around 230 hp if I remember right. So that leads to item 2.

3. Read about the so-called "quarter mod" on the http://www.thirdgen.org web site. You need to raise the fuel pressure in the fuel pressure regulator (FPR); this will *help* but it won't solve all your problems. You may eventually need larger injectors and/or the vFPR (vacuum-compensated FPR).

4. You may very well need to replace the fuel pump with one from a 94-96 LT1 Caprice. I don't know if the stock 91 pump can supply enough fuel to satisfy the engine. The LT1 Caprice fuel pump can pump enough to feed nearly 400 hp, so it would be fine for your engine, and it should be a bolt in. You could also use an aftermarket one like a Walbro.

5. this is the biggie --- I really think you won't ever get that engine running extremely well unless you can get someone to make you a custom chip. The items above are band aids -- they'll help, but I don't expect that they'll lead you to best case. The Hypertech chip is not suggested by any TBI people on the ThirdGen website (for the reasons I already said), and likewise I don't think it's a very good match for your car. If you had done almost no mods to the car, it might work fine. But with everything you've done, it's probably not any better than the stock chip. It might also be A LOT WORSE. In my opinion...

Dunno if this will be helpful to you or not.

The only other suggestion I could make is for you to find a 3rd Gen Fcar owner in your area who has done their own TBI chip burning; maybe they can log some data in your car and try making a chip for you.

In the meantime, try the above items. HTH.
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