Here are pics of my assembled motor. You can see how compact my drawthrough setup is. On the turbo to intake pipe, that is the injector nozzle for the alcohol injection. Ignore the red sparkplugs, they are there just to not get overspray on in the engine.

 

Look awsome. Congrats

 

Thats real sweet. Does the draw have any advanages or disadvantages?

 

Advantages:
Tuning is easier. Drivability a bit better. Obviously this setup is a bit more compact and pretty sweet looking.

Disadvantages:
Can't intercool
Can't intercool
Fuel pools in the turbo
Poorer fuel milage than drawthrough (i think its a myth. I get the same milage as my dellorto)
Intake supposedly ices in winter. I hope i never find out (car is not for snow!!!) plus, thats what an intake warmer is for!! But really, it can be a pain in the ***.
Oh yeah, I CANT INTERCOOL IT!!!!

 

God that turbo looks humungous

 

Actually you are already intercooled with a draw through. The fuel intercools the charge, so you don't need anything else.

 

uh oh, this could start another debate! hahahaha, i love the simplicity of draw thru setups tho.

 

Didn't I ask you about a set up like this a week ago?

 

Debate? Why? Top fuel drag racers run draw through, albeit with fuel with a much higher latent heat than plain old gasoline.

the real issue with a draw through is that you need to put ALL the fuel through the blower, so you will lose a little bit of the flow potential. In the grander scheme of things you are not building this for ultimate HP, but for ultimate simplicity.

 

so did you buy this as a kit or did you fab it your self, also where did you get the turbo?

 

I have to admit, thats really cool how its set up. Is everyone 100% positive you cant put an intercooler between the turbo output to manifold? I mean even if was just small, it would help some I could amagine. Yes I do relize that fuel would go through it, but what difference would it make? Even you you added a bigger pipe on it and had fins on its near the fan air flow it could make a difference couldnt it?

 

When you put the intercooler there, the fuel stays in the intercooler and only air comes out the other side.

 

I bought the kit from an old rotary mechanic. It can no longer be bought, and is extremely rare. The turbo is a RAYJAY B trim with a .86 A/R on the exhaust. Its comparable to a T-04 B. It will support up to 400 hp with the sweetspot at about 300hp. I am building this rx7 with simplicity AND horsepower in mind.

Oh, and I DID get something else to cool the intake charge: ALCOHOL INJECTION!!!! By the way, an intercooler, if possible, would be nice, because the fuel doesnt do as good a job as an intercooler would. Top fuel dragsters use drawthrough because its easier. You dont intercool alcohol fueled engines, there is no need.

 

How about the fact that top fuel doesn't even use a turbo? It's illegal. They have to use roots blowers.

 

In your car of alc or methanol even, you should consider an injection sytem and they are awsome to say the least haha. Look around for a few companys, I THINK that rx7store carries one, if not its another add on the top of the page. HTH

 

Fuel on its own no, but if you have alcohol as well (and maybe even some water), you should be able to cool the intake charge down to levels lower than an intercooler could manage. You have pre-compressor liquid injection, make the most of it to make a more efficient inlet path.

 

a nice simple water injection setup would do well IMHO

and be simple to use all the time

 

I chose to inject the alcohol AFTER the turbo due to a loss in compressor efficeincy if injected BEFORE the turbo. If I injected it before the turbo, it would pool in the turbo, as well as cause the turbo to have to compress more liquid on top of the fuel/air mixture. I injected it after because that's the method i have seen the most, as well as being told to put it behind the turbo by a water/alcohol injection expert. I MAY run a 50/50 water/alcohol mixture, I will test both and see what power loss i have with the water and if its worth it.

 

Seth, I've gotta see your car when it's all done. I just got mine running again, just a little more fine tuning with the carb jetting and it'll run great. I've also got a new rearend and all new suspension on the way

 

Your expert may not be that much of an expert, OR he was giving a simplified answer. For sensible levels of water injection it should all vapourise during compression, which actually improves efficiency.

If you are going major league on the WI (30-50% by volume), then you need to inject some of that post turbo, but for smaller volumes pre turbo makes a lot of sense, not least because you can pump it with Manifold pressure.

 

The setup uses a 100psi pump, non regulated (its pumping at 100psi) and there is roughly 13% coolant to fuel ratio. Will this make any difference?