do you have to run an intercooler when turbo or superchring?
 

if you have a choice is it always a positive to run an intercooler when possible?

Always better to run with one in most all cases. No, you do not have to run one. I substituted water injection on mine and made very good power without an intercooler on pump gas.

Jody

thanks camcojb, does detonation have alot to do with it as well?

everything to do with it. Compressing the air heats it up, and the higher the temps the less timing and boost you can run to prevent detonation. So you can run a blown engine with no intercooler but you have to run less boost and less timing, which means less power. Anything you can do to cool the intake air or absorb the extra heat (water injection) will allow you to make more power safely.

Jody

As Jody pointed out....cooler charge means more power per/lb of boost.

A few years ago we tested intake air temps on a well built 355" SBC running 18lbs of boost. We started our testing w/ 240* intake air temps and made 720hp. We made controlled pulls on the dyno and lowered the intake air temp to a respectable 140*. Our next pull was really lean indicating there was more air density. Once we added the fuel, we noted 807hp.

With our new intake air temps, the engine now responded to added timing. Our first 2* netted 20hp across the board. Our next 2* netted an additional 20hp across the board totaling 847hp. That's a 20% increase in power! We stopped there as the combination was out of fuel pump and injector.

I think you just motivated me to go throw more timing at my car now that I have the intercooler installed... I've dropped my IAT's by over 80F with the addition of the intercooler so it should be able to tolerate a bit more timing. I like the idea of another 40 or so HP through bumping the timing, but I am worried about pushing my luck too far and having some detonation. :willy:

I did pick up another 6% injector DC after installing the intercooler and there is a noticeable seat of the pants difference in power; the 6% IDC gain with my 75pph injectors is approximately another 36pph of fuel.

Dennis, what kind of timing numbers were you running on that 355, and could you share the details of that combo? Just wondering.

We stopped at 28* total. Although, that combination had some left in it. The springs were done and that specific intake wasn't the best choice for that hp level. I'd say it was good for 900hp with some new parts and tuning. It wasn't worth chasing a new fuel system, springs and intake. We switched to a turbo setup just a few weeks later.

The basics were 355" SBC w/ Dart Pro 1's (ported to approx 225cc), 248/254 solid roller, Holley EFI intake, D1 Procharger running 18lbs thru an air to air. We had maxxed out an "early" A1000 with approx 504lbs/hr running 13.8V and 70psi fuel pressure.
http://img.photobucket.com/albums/v2...stuff/dyno.jpg

Do you have the numbers after switching to the turbo system, you should pick up another 100 if you make the same boost. The supercharger parasitic loss is substantial(as you probably already know).

No specific comparison was made due to the difference in direction after we went with the 90mm and then 98mm turbo.

We swapped the 355" (4.030x3.48) short for a 374" short (4.125 x 3.5) due to the need for additional parts strength. We also switched to a water to air core aswell.

I will note: We used the same heads. Upgraded fuel system, intake and just abit more camshaft. With the intercooler air temps now in the 110* range, we now were making 1000hp using just 14lbs of boost. We followed that with higher boost levels, ultimatly reaching 28lbs making 1660hp with a tradional 23* head.

I've tested several superchargers back to back in efforts to see the parasitic losses. I can say, running a much larger than needed blower will "cost" you some power. We saw differences of nearly 100hp from using a unit that was "properly sized" and capable of producing required boost pressure vs one being "turned down" to the same pressure level. Also, the average power from the turbo was superior to any of the centrifiguals we tested.

Thanks for the info Dennis. The bit about using a blower larger than needed and the additional power consumption is good to know, but makes sense being that you are probably working in an inefficient area of the compressor map when you use a blower that's too large for the job.

I hear you on maxing out a fuel pump, I'm eating about 510 lb/hr right now going by the injector duty cycle numbers. I had to add a Boost-A-Pump to keep up as I was right at the edge of maxing my SX pump out.

Non-intercooled with the EFI my setup would only tolerate about 22 degrees max timing. It used to tolerate 27 degrees with the carburetor but after switching to the tunnel-ram style EFI manifold I had to take a lot of timing out of it. I haven't tried putting any more timing to it with the intercooler but that's on the agenda for this week. The only thing I don't like is I have no way of noticing detonation except for checking the plugs-- the engine & supercharger are just too loud to hear anything except severe detonation over, and if I can hear that it's too late. Any suggestions? It's easier to pick up light detonation on a dyno as you can see the torque curve "bouncing around" but tuning for max power in the car makes me rather nervous as I have no reliable way to detect light detonation in real time, only an after-pass plug check.