TPI/EFI and 406 SBC?

[MaineShark]

If the stock TPI runs out of breath in the upper revs with a 350, how soon would I lose power, with a 406? Rough guess would be 14% sooner, since that is the difference in displacement, but airflow tends to be a bit trickier than simple multiplication.

Would some of the common ported runners and a larger throttle body make enough flow difference to solve the problem, and give me decent power up to 5500 or so?

How about some of the aftermarket EFI systems?

Joe

 

[vets4-2]

if your builbing 406 strocker you should allready know the answer before you started that project! but seeing how you didn't do your home work answer some ? what's your operating range going to utobe? gas or alco?street or strip?bore stroke? single plane or dual? gears,& auto or std. if auto what stall? now if your just buying a 406 and don't know how it works and it has a carb i would say a 750 cfm with stagered jets #76 & #80 if your opperating range is going to be 2800+ for 75% of the time. And the reason I said carb. is because a 79 dosn't have any type of fi.

 

[MaineShark]

A 406 really isn't a stroker. It's a standard 400-block, bored 30-over. Stroke is, of course, the original 3.750. 30-overbore on a 400 block is 4.155". Operating range, as I mentioned, is 0-5500. Gas, and street, of course. Single plane vs. dual plane (and the jet recommendations) would be for a carb, not EFI. Gears will be 3.73 or 3.90, with a 200-4R transmission.

But, all that really doesn't matter much, as far as intake flow goes. Engine flow is basically displacement, multiplied by rpm, multiplied by 0.000289. So, at 5500 rpm, flow will be aprroximately 645 cfm. The question is, will a GM TPI intake flow at least that well? And, since the answer is probably "no," the question becomes whether a reasonable level of modification will allow it to flow that well, or if an aftermarket system is necessary...

Joe

 

[vets4-2]

first I didn' know you were running a 400 (not many left they haven't made the motor for YEARS) Bds gasket thicknesut thats no mater you simplife things a motor isn't that simple. and wont work that easy now if you want to really get into it wahts the running CR of the engine valve timing seat to seat rod lenght cc of head valve dia. int ex & runner size what type of exhaust

 

[patsnitrovette]

My brother runs a 406 with canfield aluminum heads 11.1 comp.,1000cfm throttle body,tpi intake slp runners ported and siamesed,ran good to 5800,then switched to a lt-4 intake ported and gets 6200 out of it now.Major torque.He uses a 700r4 trans with a 3000 stall,3.90 gears.

 

[vets4-2]

My brother runs a 406 with canfield aluminum heads 11.1 comp.,1000cfm throttle body,tpi intake slp runners ported and siamesed,ran good to 5800,then switched to a lt-4 intake ported and gets 6200 out of it now.Major torque.He uses a 700r4 trans with a 3000 stall,3.90 gears.

thats more like it. NICE setup.

 

[MaineShark]

first I didn' know you were running a 400 (not many left they haven't made the motor for YEARS)

400 blocks are not that hard to come by. Anyway, they are still available from GM, if you want to start with new.

Bds gasket thicknesut thats no mater you simplife things a motor isn't that simple. and wont work that easy now if you want to really get into it wahts the running CR of the engine valve timing seat to seat rod lenght cc of head valve dia. int ex & runner size what type of exhaust

The dynamic CR will certainly have an effect, but its effect will be to reduce the air requirements of the engine (since not all of the charge that is drawn on each stroke, is actually used). So, if an intake will flow enough for the full displacement, it will easily flow enough for the dynamic displacement.

Pat: thanks. Just to double-check, did he port the intake at all, or just the runners? You don't happen to have a dyno chart (or hp/torque numbers) on it, do you? I'm collecting 406 info

Joe

 

[AKRAY4PLAY]

Joe,
i just glanced at a new Super Chevy issue, June i think, they built and installed an EFI unit on a 406. you might want to check it out, pretty good reading. Brian

 

[69MyWay]

I personally think you should stay away from the stock style TPI if you want to max the car out. It is a great system, but will leave you feeling a bit breathless. By the time you mod out a stock system, you could have bought a much more sophisticated aftermarket complete.

Go back and look at www.tpis.com at the stand alone ready to rock EFI and miniram units. The miniram is the best of both worlds, and I have one on my 90 Vette. I can't say enough good about it!

 

[patsnitrovette]

My brother had to switch to the lt4 intake to get any potential out of the 406 it ran good with the ported tpi with ported slp runners and 1000 cfm throttle body ,but when he switched to a ported lt4 intake all hell broke loose.Hey 69myway,ive been looking at the miniram setup for a winter project did you lose any low end with it,im looking for more all around power with it but not to lose any low end.

 

[69MyWay]

.Hey 69myway,ive been looking at the miniram setup for a winter project did you lose any low end with it,im looking for more all around power with it but not to lose any low end.

If I lost bottom end, it is more than made up by the engines new found ability to scream to the rev limiter.

These are real numbers.

With the old 3.33 rear gears, bad tires and a slipping clutch (it blew on run #4 and I was lucky to finish the 1/4 above 50 mph). I was turning right at a 3 second 60 foot and still running 13.4 @ 106 mph. The car should have low 2 second 60s in it all day long. Just doing the math...that means it is a 12 second daily driver.

 

[bossvette]

I have been running a 383 TPI for almost 3 years on the street in a 76 it runs the way a Vette should I have slp runners with a ported plenum and manifold 36 lb inlectors 1000cfm throttle body with Holley electronics and it runs strong to 5500.
If i was doing one now I would seriously consider Holleys new system Summit has it in their latest catalog a 36 lb system should do a 406