Forced induction discussion

[ftpiercecracker1]

When i first started building my stroker i was dead set on building a "turbo stroker" but after realizing i am not made of money the turbo part of the build was tossed, at least for now .

Th reason for this thread is to start a discussion on the idea of forced induction and what it would take to achieve greater boost figures. I was watching a video on U tube of a BMW straight six that had 913 bhp, it looked like so amateurs project.
http://www.youtube.com/watch?v=1LRJ83yl ... re=related

I contemplated why they can do this with their inline six and we cant? 505 performance has on their main page what is supposed to be the most powerful jeep inline six in existence, 692hp and 780ft/lb I know thats alot already but its still nearly 200hp away from BMWs straight six and 505 probably poured 30k into that engine or more.

Why are out engines so limited? If you had all forged/billet internals with a solid head gasket what is left in the equation? I know even the very best jeep head doest flow very well, but is that really the noose around are neck? What is preventing us from running 15, 20 or even higher boost figures?

Discuss. . .

[CobraMarty]

Heat, head flow, rpm and the point no return.

Yes the head is the flow limiting bottleneck, the BMW has 4 valve per cylinder heads and DOHC.
At 15 pounds the jeep head will only flow so much, at 20 pounds it will flow a little bit more due to the higher pressure but the air at 20 pounds will be hotter and less dense, remember PV=NRT, so minimal increase in power and greater chance for detonation and .

[SilverXJ]

The Jeep 4.0L is built for torque. Its big, its heavy. Both of which do not make for a good high rpm engine. Head flow is limiting, two valves per cylinder, non cross flow. Its a single in in block cam as well. No DOHC, or SOHC. No variable valve timing, no direct injection, etc. It is a dinosaur compared to a modern BWM I6.

As far as 505's claim, I highly doubt it. If it has been done on an Jeep I6, talk to Hesco

[ftpiercecracker1]

Hmm, I see. I guess the 4.0 is a little out dated in these respects. , i guess every engine has its limits.

The BMW straight six is a puropse built high flow, high rpm, engine with modern advancements

and the jeep 4.0 is just a tired old plow pony.

That was a lot briefer discussion than i was anticipating.

[FlyinRyan]

Design, money, lack of tuning support (or perceived lack of tuning support) at least for the OBDII guys, inability to take high rpm.

I will be tuning a turbo 4.7 stroker- using the stock PCM, no less- over the winter. In NA form the vehicle is already making 300+ hp.

[cruiser54]

I got to drive a supercharged 4.6 powered Comanche alot back in the early 90s. It was a project vehicle of Jeep's.4.6 with a Paxton supercharger, Electramotive programable fuel injection.

Short wheel base Comanche 2wd, lowered with IMSA style fender flares and screaming yellow in color. Tweaks were done to the AW4 per some guy in Japan at Aisen-Warner. All replacemnt springs etc. easy to do. Probably sruff from the Toyota Celica Supra turbo I guess.

Very fast as witnessed by the guy with a 67 GTO on a 4 lane highway at 60 MPH up.

[Newcomerracing]

I see no reason why with the correct components you could not make 1,000 hp. I have a customer 98 Turbo 3.2 BMW inline six engine that he wants to make 1,000rwhp with this new motor with 30 pounds of boost. His current engine makes 660rwhp@16psi/750-790@hp has stock cams and a stock head. Now with a ported head, cams, intake, bigger turbo, and more boost were at 1,000rwhp range. Based on cubic inches and airflow a Jeep should make big numbers, for instance if a built N/A Jeep motor should make in the 400 range for power(sometimes more), if you take compression out then your at say 350hp, at 14psi it should roughly double that to make 700hp, so jack more boost and voila big hp. Just imagine a 3.2 Turbo BMW without a turbo, maybe 200/250hp range. I would love to build an all out dyno queen just to prove the point. Something to think about?