Tbi Intake Dilema

[biggsteve97]

Well I have a1987 custom built 4x4 Chevy truck with throttle body fuel injection. What my question is would I be better of port matching my current intake, an Edelbrock Performer TBI, to match my throttle body or would I be better off with a stock intake that has been ported to 52mm. Im undecided but I know I should do something. I am runnning a 454 throttle body with 90lb per hour injectors. It runs good but i believe I can get more if I remove the restriction caused byt the smaller ports on the manifold. Any suggestions? I am on a limited budget and I use this truck mostly for pulling/hauling so I am not concerned with high rpm by any means. The cam is only good from 1500-4800 but produces alot of lowend torque. Thoughts?
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[biggsteve97]

anyone?

[Skunksmash]

You're probably better off asking over at the TBI dedicated forums. Around here these guys like carb'd old stuff, or 5.3 LS's lol

[rfmaster]

Originally Posted by biggsteve97

Well I have a1987 custom built 4x4 Chevy truck with throttle body fuel injection. What my question is would I be better of port matching my current intake, an Edelbrock Performer TBI, to match my throttle body or would I be better off with a stock intake that has been ported to 52mm. Im undecided but I know I should do something. I am runnning a 454 throttle body with 90lb per hour injectors. It runs good but i believe I can get more if I remove the restriction caused byt the smaller ports on the manifold. Any suggestions? I am on a limited budget and I use this truck mostly for pulling/hauling so I am not concerned with high rpm by any means. The cam is only good from 1500-4800 but produces alot of lowend torque. Thoughts?
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I have used BBC TB with 62 lb-hr injectors (I run 14 PSI) with Edelbrock Performer 2101 (with adapter plate), Holley Projection Intake 300-49 and OE AL TBI intake bored out to 52mm on the same 350CID with CS1014r cam. In all three configurations I also used 1" TB spacer. In my truck 300-49 felt to offer better mid range torque 1800 to 3000 RPM. Performer seems to have slightly better top end. OE intake - I can not recall - its been a while. In all three cases performance and economy has been excellent over Q-Jet. Custom DIY ECM tuning with WBO was used to dial combos in.

//RF

[biggsteve97]

Ill give the dedicated forums a shot. Lots of people seem to forget that the 87-91 RV old body trucks came factory with TBI so when I start asking questions their first response ia what did you get the fuel injection off of is why I tried here first. I would love to drop a 5.3 or a 6.0 in my truck but the wallet wont allow it. Thanks for the info on the projectiob manifold ive wondered about that one myself but it requires a bit more modification for everything to connect up properly is the only reason ive steered away from it...ao far. Ive found a guy here that says he will bead blast,polish, and port match my edelbrock intake for only $50 so im thinking about trying that
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[Skunksmash]

Yeah I got one in my 87 and its really been a good motor. As old as it is, I still really have no complaints about it. It will be replaced with a 5.3, , but its done its job well. If it were not for the significant increase in gas mileage when switching to the 5.3, I would just rebuild this motor and keep TBI.

[biggsteve97]

Originally Posted by Skunksmash

Yeah I got one in my 87 and its really been a good motor. As old as it is, I still really have no complaints about it. It will be replaced with a 5.3, , but its done its job well. If it were not for the significant increase in gas mileage when switching to the 5.3, I would just rebuild this motor and keep TBI.

With everything ive done to my truck so far, I have managed to consistantly achieve a combined 17 mpg if I keep my foot out of it otherwise its about 13-14. The only highway trip Ive taken in my truck was a few years ago and I got 22 mpg without the trailer and on the way back I got 17 with the 4500 lb loaded trailer. If I can achieve better than that in my full time four wheel drive truck by converting to a 5.3 or 6.0 then I think ill look into it however with that said my current setup nets more hp and tq than a stock 5.3 and more tq than a stock 6.0 so I would have to find one thats already built up or build one myself.
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[biggsteve97]

Originally Posted by Skunksmash

Yeah I got one in my 87 and its really been a good motor. As old as it is, I still really have no complaints about it. It will be replaced with a 5.3, , but its done its job well. If it were not for the significant increase in gas mileage when switching to the 5.3, I would just rebuild this motor and keep TBI.

With everything ive done to my truck so far, I have managed to consistantly achieve a combined 17 mpg if I keep my foot out of it otherwise its about 13-14. The only highway trip Ive taken in my truck was a few years ago and I got 22 mpg without the trailer and on the way back I got 17 with the 4500 lb loaded trailer. If I can achieve better than that in my full time four wheel drive truck by converting to a 5.3 or 6.0 then I think ill look into it however with that said my current setup nets more hp and tq than a stock 5.3 and more tq than a stock 6.0 so I would have to find one thats already built up or build one myself.
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[mrhino]

Originally Posted by biggsteve97

Well I have a1987 custom built 4x4 Chevy truck with throttle body fuel injection. What my question is would I be better of port matching my current intake, an Edelbrock Performer TBI, to match my throttle body or would I be better off with a stock intake that has been ported to 52mm. Im undecided but I know I should do something. I am runnning a 454 throttle body with 90lb per hour injectors. It runs good but i believe I can get more if I remove the restriction caused byt the smaller ports on the manifold. Any suggestions? I am on a limited budget and I use this truck mostly for pulling/hauling so I am not concerned with high rpm by any means. The cam is only good from 1500-4800 but produces alot of lowend torque. Thoughts?
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Im intersted in what your finding our on the manifold as well, I will be building a new engine for my wifes crewcab soon. i am encouraged by your currant numbers. (17 mpg) what engine do you have? what trans and gear ratio as well? I am shooting for 20 or more around town using a TB 5.7. Iv been doing research myself on what the best manifold would be. Also my last project 71 c10 I retro fitted a 5.3 in and it would only get 15-17. I feel i can do better.

[Skunksmash]

Originally Posted by biggsteve97

With everything ive done to my truck so far, I have managed to consistantly achieve a combined 17 mpg if I keep my foot out of it otherwise its about 13-14. The only highway trip Ive taken in my truck was a few years ago and I got 22 mpg without the trailer and on the way back I got 17 with the 4500 lb loaded trailer. If I can achieve better than that in my full time four wheel drive truck by converting to a 5.3 or 6.0 then I think ill look into it however with that said my current setup nets more hp and tq than a stock 5.3 and more tq than a stock 6.0 so I would have to find one thats already built up or build one myself.
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If you look into the 5.3 a little deeper, you'll find a lot of people netting close to 20mpg city. Which is partially due to the reduced weight of these trucks over what the 5.3 came out of. And of course more on the highway. From what I've read its a lot easier to chase down the high MPG when dealing with an LS motor than when dealing with a 350. With the LS its just a few easy bolt ons with not a whole lot of thought involved. And you get all that plus a 110 hp boost over your stock 350. Which was of course 220hp. That's what I wish mine still was lol

Generally you'll see most of the 5.3 guys stop at about 330hp since that's sort of the sweet spot for power and gas mileage on those motors, give or take some of course. IIRC, stock the 5.3 is 305hp. I've heard of a few guys like you though that tweak out comparable numbers out of the TBI 350, but its a bit of a crap shoot. Instead of rolling the dice to see if I can pull it off I'll just go the quick and easy route.

[biggsteve97]

Originally Posted by mrhino

Im intersted in what your finding our on the manifold as well, I will be building a new engine for my wifes crewcab soon. i am encouraged by your currant numbers. (17 mpg) what engine do you have? what trans and gear ratio as well? I am shooting for 20 or more around town using a TB 5.7. Iv been doing research myself on what the best manifold would be. Also my last project 71 c10 I retro fitted a 5.3 in and it would only get 15-17. I feel i can do better.

Well so far the best info ive found is on thirdgen.com. A guy flowbenched the Edelbrock tbi manifold and it had an average of about 215 cfm where a stock manifold was about 180 cfm. Both manifolds tested had been bored out to 2".
My engine is a .060" over 350 from 1975 chevy truck with 1989 chevy truck heads that have been gasket matched for better flow. Since the heads dont flow much past 4800rpm its a litle weak in the top end but i built the engine for torque not hp anyway. And the nice realitvely flat torque curve I have leads to the better gas mileage. 80% of peak tq is available from 1200 rpm up. I now have an NV4500HD 5 speed manual from a 93 chevy one ton with all the upgrades to prevent overdrive from failing and I run 3.73 gears since I have a 6.34:1 granny low. In a lighter truck or car my engine setup should net closer to low to mid 20's on the highway. If your not in the 20's with ur 5.3 then you need to make sure you are running a good air filter, ac delco plugs, fresh fuel filter, atleast 55 psi fuel pressure, and a good free flow exhaust. If youre still not there after that then id suggest a live data program and a laptop to see whats going on.
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[biggsteve97]

Originally Posted by mrhino

Im intersted in what your finding our on the manifold as well, I will be building a new engine for my wifes crewcab soon. i am encouraged by your currant numbers. (17 mpg) what engine do you have? what trans and gear ratio as well? I am shooting for 20 or more around town using a TB 5.7. Iv been doing research myself on what the best manifold would be. Also my last project 71 c10 I retro fitted a 5.3 in and it would only get 15-17. I feel i can do better.

Sorry it took soo long to respond back. I havent been online in awhile. I have a .060 over 350 with hyperutectic 9.5:1 pistons, stock 89 350 truck heads, and a Lunati truck avenger camshaft. The trans is an NV4500HD and I am running 3.73 gears in both axles. I am also running Heddman Headers large tube small block hedders with 3" dual exhaust and round Dynomax Ultr-Flo mufflers rated at 2100cfm each and a five inch tall K&N filter with K&N high flow filter top. Also have the Helix power tower throttle body spacer. I wasnt able to get the truck back on the road until late march early april. I had the intake port matched to the throttle body and gasket matched to the heads with mild polish to the runners. I can say there was a very significant improvement in performance. Much better throttle response and driveability. I am also running the 454 throttle body with an 18psi pressure regulator spring on the 90pph gm injectors and a custom chip from TBICHIPS.com. If and only if I keep my foot out of it, which is very hard to do, I am getting approx 300 miles on the 16 gallon tank which is almost 19mpg and that is city driving mostly 45mph and slower with the reworked eldelbrock intake. If I drive like I stole it I still average 15-16mpg all city or approx. 275 miles per 16 gal tank.