Carbs, fuel injection, turbos and superchargers

Tue 15 Jul 08 00:37

Carbs, fuel injection, turbos and superchargers

Edit:
The posts below are split from this thread:
http://www.corvetteclub.org.uk/viewtopic.php?t=6586

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Give me your smallblock motor and i will guarantee i can do it for £3500. Its what i do. Blakey witnessed the power in my vette which is over 600hp and it cost me £6k to build it would have been less but i had to make alot of mods to fit the motor in the C4.
350hp out of a sbc is very easy to do!
Ali big valve heads, thumper cam, 750 cfm carb ,good exhaust, forged pistons, arp bolts in everything and you have 350 hp, for more you just tickle it in the right places

The only thing i dont supply is headers, but you,ll need them to be at least 2 to 2 1/2 inch.

Then you,ll need someone clever to get rid of all your inj crap and wiring , not easy to do , took me longer to sort the wiring than it did to build the motor. Even my LCD dash works correctly

If your going for 450 hp + you'll need to have the gearbox uprated along with the brakes , propshaft, driveshafts and diff depending on whether you,ve got a dana 34 or 44.

The engine is the easy part its the rest of the car thats time consuming.
There are over 500 hrs in my car yet you cant see where its gone but consider this, i paid £4k for the car and it was in bits i then spent near enough £6k on the motor then if i had had to pay out for labour it would have 500 hrs at £35 an hr.

This is what happens if you dont do things properly!




And thats steel imagine how easy a vette ali one will twist up!

Last edited by Ben on Fri 18 Jul 08 09:12; edited 7 times in total. [82 %]
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550 HORSES ARE TOO MUCH !!!

Tue 15 Jul 08 09:34

get rid of fuel injection for carb? - Why?

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1985 C4 - GS Themed, LT1 Intake 383 Stroker Engine.

My CCCUK Corvette Challenge 2009 - Compilation
http://www.youtube.com/watch?v=XnLis77oQp0

Tue 15 Jul 08 16:46

Re: new engine or rebuild

Only get rid of stock injection if it isn't capable of handling extra power mods. Keep it if possible and get benefits of better fuel consumption. Most people will say "get rid of it" as they are either unable to to find someone to 'tweak it' or are not prepared to accept the fact that proper 'mapping' by nature of the time it takes is very expensive. Don't be too fooled by plug'n'play aftermarket injection systems at $2k to $3k, they work as well (and posibly better) than any well set-up carb but still really need more sophisticated management to get the best power/economy out of them.

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'68 coupe - 4 speed - 3.08 - F41 - 489 cu in - 528 bhp @ 5850 rpm - 565 ft/lbs torque (766 Newton Metres) @ 3850 rpm - (225 bhp & 465 ft/lb Torque @ 2500 rpm)

Act like a juvenile before turning senile !

Tue 15 Jul 08 18:55

dan_t wrote (View Post):get rid of fuel injection for carb? - Why?

Because i was asked if i could build a 350hp+ engine for £3500, yes , now if you are putting injection back on thats fine but by the time youve uprated the injection system , put on larger throttle body, opened up the inlet manifold to allow more and smoother flow etc the bill would be much more. The TPI inlet is a joke its much too long and although your only moving air through it, it is not designed for performance upgrading.The shortest route the air travels the quicker response you get, the better the motor breaths and the more horsepower you release.

Yes you will get better economy but the golden rule is, and always has been you can't have performance and economy. One always to a certain extent has to be sacrificed for the other.

How many dragsters do you see with petrol fuel injection ?????

Only meth and Alky motors use injection because of the sheer volatility of the fuel and its unpredictability at normal atmospheric pressure.

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550 HORSES ARE TOO MUCH !!!

Tue 15 Jul 08 23:53

Re: new engine or rebuild

Latest generations of pro-street vehicles are starting to use latest hi-spec' fuel injection (as they are also using big FO twin turbos'). You can have best of both worlds (almost) but not both at the same time. If you look at true cost of going fuel injection it will take many many miles to re-coupe outlay in terms of saved mpg.

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'68 coupe - 4 speed - 3.08 - F41 - 489 cu in - 528 bhp @ 5850 rpm - 565 ft/lbs torque (766 Newton Metres) @ 3850 rpm - (225 bhp & 465 ft/lb Torque @ 2500 rpm)

Act like a juvenile before turning senile !

Wed 16 Jul 08 17:51

How much is a Carb setup? A mini-ram style intake can be done for less than £400. Thats enough intake to do 600hp if you've got the motor to do it. An after market TPI with good heads, and cam can touch 350hp but I'd expect that to be more expensive but also more torquey...

IMO if you've got fuel injection than carb is a step backwards. It might be be the right way to go if your running carb originally mind.

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1985 C4 - GS Themed, LT1 Intake 383 Stroker Engine.

My CCCUK Corvette Challenge 2009 - Compilation
http://www.youtube.com/watch?v=XnLis77oQp0

Wed 16 Jul 08 18:01

Re: new engine or rebuild

Just take a look on the Summit website if you want to get an idea of costs for an injection set-up (or a blower kit for that matter)

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'68 coupe - 4 speed - 3.08 - F41 - 489 cu in - 528 bhp @ 5850 rpm - 565 ft/lbs torque (766 Newton Metres) @ 3850 rpm - (225 bhp & 465 ft/lb Torque @ 2500 rpm)

Act like a juvenile before turning senile !

Wed 16 Jul 08 18:57

Dan , can you post a link to these mini ram systems , im intrigued

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550 HORSES ARE TOO MUCH !!!

Wed 16 Jul 08 19:10

Carb definitely a step back from injection. The TPI set up is a good one, in stock form, but to tune it, like may other motors, blowing it is one of the straightforward options (I'd put the old Ford 2.8i V6 in the same camp) BUT you can get larger bore runners and manifolds, or the Lingenfelter/Accel intake options that offer even larger runners, or the LT1 style mini ram set up. Dan/Adi 4's solution is the most cost effective by the looks of things, the TPI (co name not system) mini ram is quite costly and availability (delivery time wise) may be questionable.

If you're running a carb one thing you lose is the fuel computer. Sad I know for mentioning it. Also fuel consumption could take a hit if its not set up cock on. My Vette does less miles these days due to fuel cost, it's a real consideration, FI will keep more of the available efficiency.

Latterly, if you NA tune one of these engines, it may not suit an auto box if pushing power further up the rev range, and for £6k, well you can rebuild the engine and get an intercooled supercharged set up - it'll probably be more driveable too.

The driveshaft pic and comment about alumium shafts is ridiculous. The C4 shafts happily take silly horses (e.g. there's at least a couple of 500+ Hp ZR1's out there without different shafts) - the weak point on the C4's tends to be the spiders. I'd seen the twisted shaft pic when it first came out, and I'm afraid the only conclusions for it that it was a pattern part with thinner walled tubing or one that has been thinned over the years from corrosion, not a problem with the aluminium variants, and also I believe a very rare one for the steel shafts.

Even with 1000Hp, on road tyres there won't be enough traction to do that kind of damage.

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1995 Corvette LT1 6-Speed Coupe
1990 Japanese thingy (MX5)
2007 Honda UFO

Previous
1986 Corvette Z51 Coupe

Wed 16 Jul 08 22:24

Hmmmm seems most get a supercharger mixed up with a procharger, prochargers are belt driven turbos and although they deliver big boost psi they are limited to a powerband , however a PROPER supercharger (rootes type) is not limited it builds power and keeps building until you hit the rev limiter, something the procharger system does NOT do until it hits high revs, also you have to intercool a procharger, whereas the supercharger draws cool air.

To fit a procharger is very easy and not to many mods needed , to fit a supercharger is beyond ridiculous BUT when done will out perform any of the other modifications you can do, its like NoS with an ever lasting bottle, also the supercharger at cruisng speeds gives MORE MPG then any EFI system.

My vette if nailed on EFI with the superchip in would drop to 6MPG on the economy meter , now with foot to the floor and leaving it their till my bottle goes i still get no less than 6 to the gallon, i will admit that around town it is not as good as efi, but the advantage of endless aston ,porsche ,skyline etc beating power is well worth the extra fuel.

Its all a matter of how much power you want, personally i would never need anymore than i have as the faster i go the more power i have , the only limit is my bottle!

Last edited by Blown C4 on Wed 16 Jul 08 23:50; edited 1 time in total. [1 %]
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550 HORSES ARE TOO MUCH !!!