supercharging a 2.5 turbo engine?

[cook]

I have a Eaton M90 supercharger and Im wondering if its possible to mount it instead of the current turbo setup? Is this charger to big? would I have to modify the fuel system? Would the computer operate? The vehicle is a 89 turbo caravan and I think the instant boost may be better plus the lower underhood temp. Im in the middle of replacing the engine as it is blown. I've looked at the cost of replacement turbo's and theyre not cheap. I also realize that the charger robs you of power! And I'll need a exhaust header. Thanks for any input!

[big_P]

An Eaton M-90 is way, way too big for a low compression 4cyl. Use an Eaton M-62, or a factory blower kit. Either way, you'll have to convert to carb and that's not going to be fun.

Don't buy a new turbo, find a used one on these forums.

[85woodywagon]

Quote:

Originally Posted by big_P An Eaton M-90 is way, way too big for a low compression 4cyl. Use an Eaton M-62, or a factory blower kit. Either way, you'll have to convert to carb and that's not going to be fun. Don't buy a new turbo, find a used one on these forums.

Convert to a CARB?

His van is already a turbo so the engine would probably run without a problem using the stock electronics BOOST IS BOOST.

Use the Eaton M-90 with a 2.4l swap from a 96 caravan. The 2.4l should breath enough to handle that blower. Just get some +40s, slap the distributor on the cam and get a custom calibration.

[Shel-Game]

An M90 isn't way too big. It's good for around 350hp, though. If you "only" want ~250, go for the M62. I don't see any reason why you couldn't run it just fine on the turbo electronics...

[cook]

I thought you could but its just an issue with suppling enough fuel and spark. I know that there are alot of tricks with fooling the computer with the whole PSI issue and that +40 injectors are big enough?? Of course I'll take the A/C out because of the simple fact that I live in Canada and we only get a real summer for about three weeks!! Im hoping that the supplied crank pulley is big enough or small enough to power this beast? Just imagine a 90ci blower on a 150ci engine I dont think running lean would be such a great idea!!!

[GLHNSLHT2]

keep it turbo. Why suck power with the S/C also your gas mileage would go down too. Turbo's rock, Superchargers suck.

[big_P]

Yeah, but S/C's have INSTANT boost. Gotta love that low end.

[88-16V-Lebaron]

Quote:

Originally Posted by GLHNSLHT2 keep it turbo. Why suck power with the S/C also your gas mileage would go down too. Turbo's rock, Superchargers suck.

Go with a small supercharger and huge honkin turbo. The best of both

[cook]

You would have to think that it will work I'll probably have to add 12 more fuel injectors Does anyone knowof a good exhaust header. This contraption will be in a 89 caravan. Just imagine the whine of blower in minivan priceless

[cook]

I recently spoke to Gary Donovan he's quite familiar with these motors he said it should work great boost is boost! And its instant. Just recently I purchased a 5spd turbo van, so now i have the best of both worlds a auto and a 5spd van

[big_P]

Oops, I mean that if you went with a factory B&M setup you'd have to convert to carb.

I still think an M-90 would be too big for the 2.5L, though.

[cook]

But dont you think you can balance the larger volume of air with more fuel eg. larger injectors or more injectors like a cold start off a SAAB. Or put on a larger pulley to decrease the PSI? It would be just like putting on a larger turbo am I wrong? Im not to concerned about the fabrication part its just the question of the volume air going into the engine and the fuel amount required. Also would the older "bathtub" head with the lower compression help the situation?

[DaytonaTurbo87]

The older head would just lower compression further, no point in that. Like said, boost is boost, don't worry about the volume of air. Like you suggested, it's the same as adding a larger turbo. Volume is the same at a given boost level, it's just that the efficiency of the turbo is better or worse at a given rpm with a larger or smaller turbo. Why would you just want to slap some +40's on it without a custom cal? That'll just richen the crap out of it. Sit down for a while and figure out a way to mount that thing and plumb it into the stock throttle body. You gotta remember that superchargers don't have a wastegate built into them like turbos, they won't boost to a point then stop, they'll keep going and going as long as rpm rises, so will supercharger output. If you think the supercharger will flow too much, it won't, boost will just be higher throughout the entire rpm range. Which with that size of a supercharger on a 2.5, I think it'll quickly run past the 14psi cutoff line. I say mount then plumb the supercharger up and connect it to the stock throttle body and keep the electronics the same. A wide band 02 would be a good idea, or a dawes device at the bare minimum. You don't need a header. A header will help because you are pushing more HP, but a regular n/a exhaust manifold will suffice.

When you have the supercharger all mounted and plumbed in, the ratio of your pulleys will determine how much boost you will build, and how quickly it will build through the entire rpm range. That's the hard part, picking a starting point for pulley ratios. Clearly more research on your part is needed there. But yes, it will work. If boost goes up, the computer will inject more fuel, so what's the problem? If you hit cutoff it'll shut you down, then you know you either have to lower your max boost by changing pulleys or get a custom cal for higher boost, or fool the computer and add extra injectors, ect. All the tricks used by the turbo guys will apply on this setup as well. If you get the right pulleys and have this thing dialed in properly, you could have one heck of a ground pounder on your hands. IMO the worst part is fabricating mounts and plumbing for that sucker.

[cook]

I'm really not to concerned with the fab work I've got a shit load of aluminum plate and tubing at my shop I also have a TIG and pulse mig welder as well. I just bought a spare engine so the jigging and placement "should" be no issue. I'm just surprised that know one has really tried this out cause you can pick up a blower for a great price at the scrap yard off of a supercoupe or various GM vehicles. The pulley diameters I feel maybe an big issue I have to check the diameter of the supercoupe crank pulley to see what the difference is. The fuel maybe solved with a cold start injector off of a SAAB? I was thinking of running piping to a volvo intercooler then directly to the throttle body with a blow off valve. Dont get me wrong I dont dislike turbos yesterday I bought a 5spd turbo caravan as well, I just "think" in the automatic version with a blower seems better?

[JONYMOPAR]

Very Interesting Ideas You Guys Have, Fyi, I Own A Superchared Car And A 85 Daytona Turbo, As Well As A Tbi 2.5 Sundance, The Turbo Is Very Laggy To The Point That My Sundance With 180k Miles Has More Get Up And Go From The Line Than The Turbo. The Supercharged Car Has Instant Respones. Comparing The Cars I Would Say The Supercharger Is Less Of A Hassle, Less Heat And Maintenence, Yes It Is True You Are Limited As Far As Boost Is Concerned, But I Don,t Worry About Blowing Up My Motor And I Have Been Running It For 16 Years Now. Good Luck Let Me Know How You Make Out.