what is the most hp that you can get out of a stock prom till you have to change it

 

Ughh... 63342234.32 HP ?

Wanna rephrase your question maybe ?

Do you mean what't the most HP your engine can make after you mod it until you need a new chip ? In that case... not much.

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92 Z28 L98 350
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Ported stock heads, XR270HR-10 cam, TES headers, Crane AFPR, Flowmaster catback, MSD ignition components.
Best ET 13.5@105 mph
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It's not the HP,, it's how it relates to the combination of parts (cam, heads, intake system, injector size, fuel pressure, etc.). If you build a good combination and stay within the parameters of the chip you can make a lot of horsepower with it. How much depends on the combination.


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86 IROC - 9.8:1 - 355, TFS twisted wedge heads, 218/228-110, fully ported GM base and plenum, SLP runners, 52mm BBK, 24# SVO, 88 350 GM EPROM, 1 5/8" Headman headers, 2.5" Dynomax, TH350, 2200 stall, B&M Megashifter, 3.23 peg leg, 245/45ZR17 on 212 Eagles - Best run - 12.53/112.4 on 26x11.5 ET Streets.

 

Maybe a better question is how much MORE HP you can make if you have a chip optimized for your combination...along with driveability, gas mileage and emissions.

GM's eprom is actually quite flexible and operates over a much wider range of than I previously thought. Howerver, it won't be optimum; costing you HP. How do you explain what good champagne tastes like when you've only drank cheap wine with a screw off cap?

 

sorry no post

[This message has been edited by BadSS (edited January 16, 2001).]

 

i wanted to know how much i could do before changing a chip

 

As I said, the GM eprom is surprisingly flexible and will continue to operate with a lot more modifications that you would think possible. However, you WILL NOT be getting the HP you truly should get from the mods you made.

This is why sometimes guys that seem to have only a few mods seem to get amazing performance, while another guy, with a hell of a lot more mods may not even get the same level of performance. This is true for carbs, but even more so for EFI.

 

I agree with Glenn's post. However, you asked about HP,, and again I'll say it depends more on the combination on how well the stock chip would work with the combination. You could have a 375 horse combination with good heads and intake system and "small" cam that works well with the stock chip (probably better with a custom). Then again you could have a 350 horse combination,, less heads,, "big" cam and would not even idle with the stock chip. The selection of parts,, and how they relate as a whole is the key. Like Glenn said,, results vary greatly!!!

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86 IROC - 9.8:1 - 355, TFS twisted wedge heads, 218/228-110, fully ported GM base and plenum, SLP runners, 52mm BBK, 24# SVO, 88 350 GM EPROM, 1 5/8" Headman headers, 2.5" Dynomax, TH350, 2200 stall, B&M Megashifter, 3.23 peg leg, 245/45ZR17 on 212 Eagles - Best run - 12.53/112.4 on 26x11.5 ET Streets.

 

so if i am planning on making a lot of mods i should get a custom chip or just be carefull in selecting the mods (sorry for all the questions; i am fairly new at this)

 

I'd say if you want to buy the stuff and have the time to research and learn,, burn your own. If not, I'd build around the 1988 350 GM chip,,, that is assuming your 85 has the late model system.

I've had bad luck with the long distance chip burning thing and would not recommend it. The previous owner spent $550 for a JET chip,, and the car won't even idle with it,, a well know, respected and knowledgeable chip burner sent me a number of chips over a 4 month period, all working better than the stock 305, but when the solder broke and I had to buy an emergency EPROM from GM,,, the car came alive with the GM 350 chip. I know this guy could and would "get it right" for me,, but it's working really well for me and I have no desire to continue to "abuse" the car testing chips and "tuning" the AFPR and base timing,, over and over. I mean there is like close to $750 worth of chips in a box,,, and I'm running a $38 GM chip,, go figure.

You can't match my combination exactly due to the extensive porting I did to the base intake. However a flat top 350, with TFS 23* heads, Edelbrock intake, SLP runners (ASM LTR if budget allows), ported plenum, 52 mm t/b, 22 lb injectors, a X4254H 210/218 - 111 cam, 1 5/8" headers, 3" exhaust,, and you should be well within the range of the 88 350 GM EPROM and come close to the power I'm making. I'd also recommend not gutting the MAF sensor,, until you see if the car is running rich or not at idle once you put the combo together. That "cleaned" my idle up a good bit, but I imagine it could hurt you if you didn't need the extra flow,, especially at tip in. But,, if you learn how to burn your own chip,, you could adjust that via programming. If you don't want to limit yourself to the confinement of a stock GM chip,,, I'm sure these guys won't mind helping you,, they're a nice group of fellows.

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86 IROC - 9.8:1 - 355, TFS twisted wedge heads, 218/228-110, fully ported GM base and plenum, SLP runners, 52mm BBK, 24# SVO, 88 350 GM EPROM, 1 5/8" Headman headers, 2.5" Dynomax, TH350, 2200 stall, B&M Megashifter, 3.23 peg leg, 245/45ZR17 on 212 Eagles - Best run - 12.53/112.4 on 26x11.5 ET Streets.

 

thanks badss that was a lot of help i think that i get it now and if i have anymore questions i will ask you. o ya i have one more can just about any mechanic port a plenum well or does it take someone that knows there way around a tpi engin???

 

85 print these off and take them to anyone that has just a little bit of porting experience and they should have no problem doing it,, and you should see results.
http://www.isthq.com/~dan/efi.html http://www.tribal-treasures.com/cars...-port/port.htm