91 gmc pickup thinking of going carb. and have ??

deion82 · 09-21-2006, 06:04 PM

I have a 91 gmc 2wd pickup. 350 5 speed. I'm going to be building a new engine and all the custom chip tuning places say that 400hp is max the tbi computer will allow. They all recommend a stand alone fuel management system whick you'll sink $3,000 into with all the different pieces. My question is does anyone know if the cruise control and or ac will work if I go to carb. I'll leave the computer and wire harness in to control the guages and etc. I'd just unplug the tbi and dist. connector and seal up in case i ever go back to efi. Thanks

mudseeker · 09-21-2006, 06:42 PM

i don't think you would want more than 400 ponies if this is going to be your daily driver (2x4). your comression would be higher than normal which would mean the higher octane gas and we all know that ain't cheep. everything should work if you go carb though. you also mentioned a chip, that will be useless if you go carb. also remember that the carb is less efficient than the tbi so it will take more work to get to the 400 ponies.

deion82 · 09-21-2006, 07:51 PM

The combo that i'm looking at with the engine builder is a 434ci sbc, fti custom hyd roller cam and edel. e-tec 200 heads and air gap intake with a 750cfm carb. The combo has a 10:1 cr so I don't need the high octane gas. He did a similar combo and it made 623 hp 593 tq. The key is a custom cam.

bradrhale · 09-21-2006, 08:40 PM

be careful with a 10.1 compression ratio using 87 octane. im sure that it will work but might have problems arise later in its life. for safety sake, i believe that i would go for midgrade at least. you are correct about the cam. the right cam will unlock the hidden 50 or so horses that is stuffed underneath that intake. keep in mind what size cam is put in and match it to your intake and especially your torque converter. do not try to use a heavy lobe cam with a stock converter. or vice versa. i am really curious as how your guy is pulling 600 horses and ftlbs out of this engine though.

chevyguy · 09-22-2006, 12:15 AM

yip, you aint runnign 87 octane with 10:1 compression.

deion82 · 09-22-2006, 10:27 AM

You can easily run 87 octane with 10:1 cr with aluminum heads. I have a dyno sim pro program and putting in all the pieces show 600+ hp with that combo. With a off the shelf comp cam, erson or crane cam it don't show that kind of power but with the specs i have for a fti cam it showed 600+ hp. The 434 that this shop built had afr heads not the edelbrock like I have.

bradrhale · 09-22-2006, 10:50 AM

i have never trusted those programs unless you know everything little thing about that engine. port size and deck height, valve timing and bore size. there are so many variables that goes into that, noone can really throw a bunch of numbers together and get a good estimate. dont get me wrong, i am not knocking you or your software but the only thing that worries me is that you want to put together a hopped up engine like this and have it come apart. i hate to see this happen and have seen it happen to WAY too many good people. 600+ is going to require that you balance your crank within .005 tolerance or less for one. i do know that you can run lower octane fuel in high compression engines but it will not perform like your computer says it will. me and cg are just trying to give you a heads up on what could happen. thats all.

deion82 · 09-22-2006, 02:13 PM

Thanks for info. I'm not a novice engine tuner or builder. I've been building engine's for years. My own of course after they are machined. This program is quite accurate if you know all the variables to put in. Your right w/o the correct info it's not going to be close. It's very important to get the flow numbers of the heads from a flow bench. Can't take advertised flow numbers. Company's have a tendecy to brag them up more than what they are. I've done some side by side testing with the local machine shop on engine builds and this program was within 10 hp on 3 different builds versus the actual dyno pull's. Ed Curtis at FTI cams is amazing. His custom cams can make 100 hp more than any off the shelf cam. I've seen it. You'd be amazed if you ran one of his cams. He's getting 5.0 mustangs with stock short block and a edelbrock performer intake, afr 165 heads and his cam 350hp at the tires. Stock they have 225hp at the flywheel. I know I used to own one. I do appreciate you looking out for people. Some of the details on this engine 400 block with billet splayed caps bored to 4.155. Scat 4" stroke 4340 crank and 6.0" h beam rods with wiseco piston's. edelbrock e-tec 200 heads. These things flow very nice out of the box. We were very impressed. 275.3 intake and 208.1 exhaust bone stock. I'm kinda thinking of just putting header, exhaust, intake and high flow tbi on the truck. Then buy something else to play with. Any way i look at it the pickup still weighs 3,800 lbs. Even with the 434ci it's a lot of metal to get moving. My dad past away from a 2 year battle with cancer last winter and this was his truck. I bought it from my mother to keep it in the family. So maybe i'll just make it into a show truck in memory of him.

chevyguy · 09-23-2006, 12:00 AM

Cpmouter programs are great, but I still aint gonna run 10-1 compression on 87 octane. All the race motor I have built tell me its a no no. Read a little car craft or super chevy,They say the same thing. I just aint gonna buy it. there are too many out side factors a computer program doesnt factor in. I HIGHLY recommend against it.

deion82 · 10-13-2006, 04:28 PM

Well i got my 383 stroker together with 9.8:1 cr and dyno'd it on 87 octane pump gas and could still get 36* full timing in it. So i'll stand by my statement with aluminum heads you can run 87 octane with a 10:1 cr. Engine dyno's don't lie. If any one is interested I post engine details and dyno numbers.

09-21-2006, 06:04 PM	#1
deion82 Full Member Join Date: Apr 2006 Posts: 29	91 gmc pickup thinking of going carb. and have ?? I have a 91 gmc 2wd pickup. 350 5 speed. I'm going to be building a new engine and all the custom chip tuning places say that 400hp is max the tbi computer will allow. They all recommend a stand alone fuel management system whick you'll sink $3,000 into with all the different pieces. My question is does anyone know if the cruise control and or ac will work if I go to carb. I'll leave the computer and wire harness in to control the guages and etc. I'd just unplug the tbi and dist. connector and seal up in case i ever go back to efi. Thanks

09-21-2006, 06:42 PM	#2
mudseeker Senior Moderator Join Date: Feb 2006 Location: michigan Posts: 6,373	i don't think you would want more than 400 ponies if this is going to be your daily driver (2x4). your comression would be higher than normal which would mean the higher octane gas and we all know that ain't cheep. everything should work if you go carb though. you also mentioned a chip, that will be useless if you go carb. also remember that the carb is less efficient than the tbi so it will take more work to get to the 400 ponies. __________________ i'd rather be hunting

09-22-2006, 12:15 AM	#5
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,370	yip, you aint runnign 87 octane with 10:1 compression. __________________ Friends dont let friends use body lifts USMC 92-96 USCG 98 to present

09-23-2006, 12:00 AM	#9
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,370	Cpmouter programs are great, but I still aint gonna run 10-1 compression on 87 octane. All the race motor I have built tell me its a no no. Read a little car craft or super chevy,They say the same thing. I just aint gonna buy it. there are too many out side factors a computer program doesnt factor in. I HIGHLY recommend against it. __________________ Friends dont let friends use body lifts USMC 92-96 USCG 98 to present

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09-21-2006, 07:51 PM	#3
deion82 Full Member Join Date: Apr 2006 Posts: 29	The combo that i'm looking at with the engine builder is a 434ci sbc, fti custom hyd roller cam and edel. e-tec 200 heads and air gap intake with a 750cfm carb. The combo has a 10:1 cr so I don't need the high octane gas. He did a similar combo and it made 623 hp 593 tq. The key is a custom cam.

09-21-2006, 08:40 PM	#4
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,014	be careful with a 10.1 compression ratio using 87 octane. im sure that it will work but might have problems arise later in its life. for safety sake, i believe that i would go for midgrade at least. you are correct about the cam. the right cam will unlock the hidden 50 or so horses that is stuffed underneath that intake. keep in mind what size cam is put in and match it to your intake and especially your torque converter. do not try to use a heavy lobe cam with a stock converter. or vice versa. i am really curious as how your guy is pulling 600 horses and ftlbs out of this engine though.

09-22-2006, 10:27 AM	#6
deion82 Full Member Join Date: Apr 2006 Posts: 29	You can easily run 87 octane with 10:1 cr with aluminum heads. I have a dyno sim pro program and putting in all the pieces show 600+ hp with that combo. With a off the shelf comp cam, erson or crane cam it don't show that kind of power but with the specs i have for a fti cam it showed 600+ hp. The 434 that this shop built had afr heads not the edelbrock like I have.

09-22-2006, 10:50 AM	#7
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,014	i have never trusted those programs unless you know everything little thing about that engine. port size and deck height, valve timing and bore size. there are so many variables that goes into that, noone can really throw a bunch of numbers together and get a good estimate. dont get me wrong, i am not knocking you or your software but the only thing that worries me is that you want to put together a hopped up engine like this and have it come apart. i hate to see this happen and have seen it happen to WAY too many good people. 600+ is going to require that you balance your crank within .005 tolerance or less for one. i do know that you can run lower octane fuel in high compression engines but it will not perform like your computer says it will. me and cg are just trying to give you a heads up on what could happen. thats all.

09-22-2006, 02:13 PM	#8
deion82 Full Member Join Date: Apr 2006 Posts: 29	Thanks for info. I'm not a novice engine tuner or builder. I've been building engine's for years. My own of course after they are machined. This program is quite accurate if you know all the variables to put in. Your right w/o the correct info it's not going to be close. It's very important to get the flow numbers of the heads from a flow bench. Can't take advertised flow numbers. Company's have a tendecy to brag them up more than what they are. I've done some side by side testing with the local machine shop on engine builds and this program was within 10 hp on 3 different builds versus the actual dyno pull's. Ed Curtis at FTI cams is amazing. His custom cams can make 100 hp more than any off the shelf cam. I've seen it. You'd be amazed if you ran one of his cams. He's getting 5.0 mustangs with stock short block and a edelbrock performer intake, afr 165 heads and his cam 350hp at the tires. Stock they have 225hp at the flywheel. I know I used to own one. I do appreciate you looking out for people. Some of the details on this engine 400 block with billet splayed caps bored to 4.155. Scat 4" stroke 4340 crank and 6.0" h beam rods with wiseco piston's. edelbrock e-tec 200 heads. These things flow very nice out of the box. We were very impressed. 275.3 intake and 208.1 exhaust bone stock. I'm kinda thinking of just putting header, exhaust, intake and high flow tbi on the truck. Then buy something else to play with. Any way i look at it the pickup still weighs 3,800 lbs. Even with the 434ci it's a lot of metal to get moving. My dad past away from a 2 year battle with cancer last winter and this was his truck. I bought it from my mother to keep it in the family. So maybe i'll just make it into a show truck in memory of him.

10-13-2006, 04:28 PM	#10
deion82 Full Member Join Date: Apr 2006 Posts: 29	Well i got my 383 stroker together with 9.8:1 cr and dyno'd it on 87 octane pump gas and could still get 36* full timing in it. So i'll stand by my statement with aluminum heads you can run 87 octane with a 10:1 cr. Engine dyno's don't lie. If any one is interested I post engine details and dyno numbers.