400 hp 355 with a 2 bbl 670 cfm holley tbi?

[dirtwarrior17]

I called holley awhile ago and they tell me this thing supports 275 hp and i need a 1000 dollar 4 bbl setup for that much power....

I got a buddy who bolted one of these things to a high hp 383 and had no problems with fuel starvation. All the efi techs tell me its all in the computers fuel map. the injectors are 85 pph (biggest holley makes) so i put a 45 psi high pressure fuel pump on there and hoped it would be enough to feed 400 hp. stock fuel pressure is around 8 psi and holley says 275 hp at 8 psi, so 45 psi has to be enough right?

the guy that built my motor says it makes 400+ on the desktop dyno and 425 ftlbs. I did the math and compared how much hp all the mods add and this thing should make over those numbers right? I still don't know if it will run lean or not. It has a cam, heads, manifold, 10 pistons, headers, k and n, with the holley tbi and accel 45 psi pump. Do i need more than the high pressure/flow fuel pump to handle the fuel demand or will that setup do it?

 

[sled_dog]

I can't say I've ever seen a 400 horse TBI motor and I would be really impress if you somehow pulled it off. Whenever you add up HP gains that manufactures claim, always cut them in half. If they say you will gain 5 HP, add 2 or 2.5. Their claims are always the best conditions usually on a different vehicle.

10 pistons... I hope that was a slip of the fingers, but then how do you type 2 digits where you should only have 1.

I think at that PSI you might blow gaskets on your injectors. Highest I've ever heard on a TBI motor was like 25 PSI. What did you use to crank it up to 45? You have to have a much larger pump. I have an aftermarket pump and it only cranks like 25 at the most. Also what RPM does that motor make its claimed max power? TBI isn't good for high RPM use. The injectors just can't pulse that fast. I'd contact a company that REALLY knows TBI motors and talk to them. Someone like Turbo City.

 

[sweetk30]

p.s.i info

he most likly used a t.p.i. pump in the sender unit. but this is all wasted work if he dosnt have a t.b.i with adjustible regulator on it. because the stock is about 12 p.s.i before it returnes to the tank via the return line. i would talk to howell-efi and see what thay say. and if it is a sbc with 400 hp i would use a t.p.i system first. t.b.i is good till about 4500k-5000k on the tack. dont forget the computer program also it wont be stock issue for this motor.

 

[big_truxx]

10 pistons should be read; 10:1 pistons I think.

 

[dirtwarrior17]

Heres what i did.....

took the stock pump out of the sending unit and put in a copper pipe to feed fuel, wrapped it with a fuel strainer, sealed it up then put an accel 45 psi pump in line not in the tank. The holley 670 cfm tbi has an adjustable regulator built in to handle up to 20 psi( the higher pressure will push right throught the regulator to about 30- 35 psi).

meant to type 10:1 flat top pistons not ten pistons.

Heres all the mods:
350 hp cam 272 dur and 447 lift 25 hp
flowtech afterburner headers and y pipe 10-15 hp
Holley projection efi manifold 25 hp
Holley 670 cfm tbi 25 hp
accel high pressure fuel pump 20 hp
Camel hump heads with work done to em 15-20 hp
10:1 speedpro flat tops 35 hp
k and n with xtreme flow lid 10 hp
custom chip 30-40 hp

adds up to about 400 hp from the stock 210. That is at probably 54 or 5600 rpm

If you plug the injector formula into the holley 85 phh injectors they should handle around 360 hp at 7 psi. with the holley regulator its probably runnin about 35 psi. If they can support that much hp at 7 psi 35 psi should be more than enough right? Keep in mind that the stock injectors are about 20 pph. 85 pph is the biggest tbi injector you can get.

Those gains come from a builder not manufacters and most of the motors he has built come out to 20 hp more than the estimates.

all the shops tell me that my setup will work but i HAVE to get a custom chip otherwise the power won't be near as high.

I would have gone tpi if i had the $$$ but I can only afford a 2bb setup.

I have a trip to the dyno planed for the custom chip soon and will know for sure when it starts to lean out but i don't have the money right now. I figure with all the mods, and bigger injectors with higher psi should be able to get up to 6000 with no fuel starvation but i've gotten "yeah it will handle it" and "no it won't handle it" A big part of the power and fuel being there is in the chip.

A master mechanic who was a friend of my dad ran a LOT of psi to the point where the injecors pop out the top of the tbi. Just tightened the plate that holds em in and that particalur 383 made numbers a little higher than mine. I have the same tbi and had the same problem at first... tightened the plate down and now they stay in. I haven't gotten this thing up to max hp rpm because still have to pass smog and get registration. Just revved it up in my driveway.

 

[smalltruckbigcid]

Heres all the mods:
350 hp cam 272 dur and 447 lift 25 hp
flowtech afterburner headers and y pipe 10-15 hp
Holley projection efi manifold 25 hp
Holley 670 cfm tbi 25 hp
accel high pressure fuel pump 20 hp
Camel hump heads with work done to em 15-20 hp
10:1 speedpro flat tops 35 hp
k and n with xtreme flow lid 10 hp
custom chip 30-40 hp

The only problems I have are the hp estimates for the fuel system. I don't see how the 2bbl tbi will add to the hp number over a carb, more effiecent,smoother, and cleaner I'll agree to. The accel pump won't add hp, it might keep it from leaning out, if thats the problem then any pump that supplies enough fuel will "add" power.
If this will be a daily driver then the 2bbl tbi should do just fine with the right tuning. You're probably leaving some horsepower on the table at high rpm with this setup ( say over 4500rpm), but how much driving do you do at that level anyway? The great lie detector (dyno) will supply the right answers and the truth...so good luck and keep us informed. I say this 'cuz theres lots of 2bbl tbi setups in junkyards that could be modified to work with older engines if the performance was good and the cost is better.
George

 

[sweetk30]

regulator info

do you know how a regulator work? it has a spring in it set to open at a set psi and then dumps the fuel back at a free flow rate untill it comes back to the set psi.

and as for the cap blowing of the injectors you are asking for a engine bay fire soon and could possible hurt some 1 other than your self.

 

[dirtwarrior17]

the pump adds power the same way a regulator would. simply puts more fuel into the engine. More psi means more fuel every pulse. I've called many efi shops and they all tell me with that much psi will push the spring open. if the spring opens at say 22 psi then it will open and stay open at 45 but the actual pressure to the tbi will be around 35.

the 2bbl tbi was added to an efi motor not a carbed motor and was not showing the gains over a carb. If i bolted the 670 cfm tbi onto my stock motor would be a 10-15 hp gain but the mods make it higher.
If you know anything about tbi injectors you know that 85 pph is HUGE

I think you misunderstood when i said the injectors popped out. I meant the plate the holds them in the bay wasn't tight. If that plate is loose they will pop out no matter what psi you run.

this is all just words until i get the dyno sheet but heres how i see it.....
this is a 670 cfm 2bbl with 2 85 pound per hour injectors running high psi with high flow manifold, a cam, big heads,etc etc etc. with a custom chip i don't see the restrictions. seems like the HUGE injecors and a very high fuel flow/psi connected with all the other mods should be flowing enough air to suck enough fuel into the cc's. i still have to put a chip in it but has anybody tried this setup or one close to it before I.E. HOlley 670 cfm tbi, 45 psi pump, 272 dur 447 lift cam, camel humps, headers, k and n, 10:1 comp, holley projection manifold, and 3" exhaust. The injectors in the tbi will handle a lot more than i have goin to em now. I just saw a holley adjustable regulator 35-65 psi. I think with one of those on top of the pump and chip it should make its full hp potential up over 5000.

I'm gonna guess it lays down over 300 rwl hp with 35's on the first dyno run without a chip. I will let you know what the numbers turn out to be without the chip then with one, in a couple months when im not poor.

 

[dirtwarrior17]

anybody know of a cheap, cheap tpi system?

A buddy , ebay , etc......

 

[sled_dog]

If you run THAT motor without a chip, it won't lay down crap on the dyno. It will fall all over itself and tell you to go screw yourself. That cam is on the edge of being too big for TBI. Too big of a cam and any lope the motor will spit codes and run like crap.

I just plugged your numbers into Desktop Dyno 2000 and came out with 330HP at 5000RPMs which is pushing it in a TBI motor. That I find a lot more believable than 400. My dad's Circle track race motor runs 11.5:1 compression, on race fuel, worked heads, big ass solid cam, single plane intake, and a 2BBl 500CFM carb(more flow than a stock or ported throttle body) and it makes an estimated 400HP. That I believe, it sits and lopes away like the nasty mouse motor it is, tap the gas and it goes from idle to 4500 in the blink of an eye. That you could possibly achieve the samething with NO lope(cause TBI hates lope) with TBI and no Blower would amaze me really. I'd estimate my 355 with RV cam, flattops pushing about 9:1 compression, dynomax headers, ported throttle body, TB spacer, and ported heads, is only pushing 275 at the motor. It made more power with a carb plain and simple.
Has your motor builder ever built anything other than a stock TBI motor?

Cheap TPI, keep your eyes on Ebay for factory units.

 

[dirtwarrior17]

330 rwl hp or at the flywheel?

This tbi is 670 cfm. It runs pretty damn smooth. I will bet the injectors are bigger than your dads. the cfm is only an air rating but the injectors have to be matched to the air flow. a 500 cfm 2 bbl will make less than a 670. What size injectors and what octane race gas? Does it have a chip?

With a chip it should make 400 at the flywheel( about 330rwhp with 35's) The chip compensates for the bigger cam.

I meant over 300 rwlhp when it has a chip.

That motor you described sounds like mine with a SMALLER TBI, high octane race gas, and higher comp. I can tap the throttle and it will spin up real quick with no hesitation or sputter and sounds damn good. Your dads circle tracker is built for hp and not torque and probably has a lot smaller cam that makes its power up at high rpms.