Is it worth it?

[2.8-350TBI]

So, I come forth in need of some schooling AGAIN.
But im glad to be back; I miss having stuff to talk about on this forum!
So, I decided to ditch my 2.8/3400 effort, and im going all out on a 3.4/3500 for my blazer, but I dont think I have mentioned why
I will slowly be building up my blazer so I can autocross it, and seeing as how all the 4.3 guys are having weight issues at the autocross, I have decided to keep the 60·V6 platform and squeeze some juice out of it... More like into it! Anyways, I will get back on topic...

I recently acquired the supercharger out of a detroit diesel 4-53 two stroke diesel engine.
These engines are little screamers, and lots of people have been using these blowers for years, but I have yet to see one on one of our own engines (I speak for 60·'ers)
My plan is (was?) to use the blower for bottom end boost, and have a turbo feeding boost into the blower for the top end. When turbo boost exceeds the blower boost, a bypass valve would open (just like in the turbo/supercharged detroits) to allow full turbo boost and keep the blower from being a restriction.

I know that it is way more complicated than it sounds, but thats why I ask your advice
Any input will be appreciated!

[RedZMonte]

Just one thing comes to mind.... Simple is better... Twin charging (S/C and Turbo) becomes interesting to Tune as well as run all the piping ect... sounds like a cool project but i would start with Just motor, then add S/C or Turbo and if you think you want to add the 2nd set of boost add it in last...

Do you change "Classes" in the auto cross if your adding power adders? i thought that is what i heard when i did it back in the day... something to consider, more power but a much harder auto x class/Competition.

S

[geoffinbc]

Not to mention the massive amount of heat your going to generate. Detroit used both on their diesels for years but Diesels don't detonate and back then they made power by dumping gobs of fuel in with tons of boost. There was no concern for emissions or economy.

For autocross I would choose a blower but top end boost wont mater much since you never really get high speed. Plus with a blower sized right your going to get lots of low and boost that will hang on right to redline.

[Guest]

You're WAY overthinking it, not to mention the fact that you would never "exceed" what the blower is capable of, since it's not a pressurizing device, it's a device to move large amounts of air, the increased intake pressure is just an added bonus.

As already stated simple is best.

I would run a turbo though, and size it small(ish), for the bottom end grunt, but not so much that you get too much torque down low and blow the tires off exiting a corner. Also using gearing can help keep the Rs up, if you size more for mid to high end power.

[2.8-350TBI]

You're WAY overthinking it, not to mention the fact that you would never "exceed" what the blower is capable of, since it's not a pressurizing device, it's a device to move large amounts of air, the increased intake pressure is just an added bonus.

As already stated simple is best.

I would run a turbo though, and size it small(ish), for the bottom end grunt, but not so much that you get too much torque down low and blow the tires off exiting a corner. Also using gearing can help keep the Rs up, if you size more for mid to high end power.

Raven, it would come from you; the guy w/ a turbo'd blazer and a top end swap.
Im looking up to you on this one!

On turbo vs blowing, I am undecided as of yet because
1) I already have the blower and have seen it in operation. The 4-53 is roughly 3.5L and its a two stroke, so I think it should produce good airflow.

2) On the turbo side, the work to get it in there is much easier, but who knows how much I will have to spend to get decent lag times.

I still fell like I need more input.

I need to take a look over at my local AC and see what their regulations are on boosting and engine swaps

AFAIK, any engine belonging to the same family as the original can run in stock classes, with bolt-ons limited to OEM products.

Seems like 3.4/3500 would be the perfect combo.

[dusterbd13]

from an autocross s-series guy.

1. all motor will be plenty.
2. chassis setup is key.
3. boosting WILL make you completely non competitive. youll be classed way out there. think D spec stuff.

the thing to think about here is throttle respons and useable power. too much power will blow the back tires off. too touchy of a pedal makes it tough to modulate for max grip. autocross is almost entirely about gearing. you dont want to have to be shifting a lot. i usually run most courses in second gear the entire time. I set mine up with 245/50.16's and 3.42 axle ratio just so i wouldnt have to shift. some tracks over at maxton i bounce the rev limiter for a second, but not too often.

my reccomendation is this:
build the hybrid. good headwork, intake, exhaust, mid range cam. gear and tire accordingly. then set up the chassis to do what you need it to do.

www.protourings10.com is your friend. bunch of us s-series twisty guys over there.