Boxster Subaru conversion interest?

[Kirk]

Originally Posted by JoeFromPA

If the OP is going to open up the exhaust (i.e. a single high-flo cat and nice open exhaust path for the turbo) and going to tune it, then the 2.5 liter will hit HARD starting at 2500 rpms on a stock-sized turbo. It will be laying down over 300 lb/ft of torque at 3000 rpms, again on the stock turbo and without fueling mods.

Otherwise, stock, the 2.5t feels fun at 3000 and hits hard at 3500rpms, but doesn't have the "flat on it's arse" feel of the 2.0t below 3000.

I had an '02 WRX that I modded up to about 300 HP. That thing was fun to drift through corners when the turbo kicked it. I'm not sure how well this would work on the light RWD Boxster though. Isn't this the kind of behavior the original 911 Turbo had with the turbo boost coming on in a rush? That's why those things were widow makers and I suspect that's why Turbos are now AWD. A turbo Box with its mid-engine layout will be better than the old rear engine 911 Turbo, but you'd still run the potential for some extreme oversteer if the turbo hit hard while trying to power out of a corner.

I've been following this thread and personally I'd still opt for a 911 engine if my Boxster S engine failed. I can drop in a 3.4L 300 HP NA engine relatively easy. Compared to a stock STi engine you're pretty much even then. Sure you can mod the 2.5L WRX engine for more power, but you could also do a low pressure (6 psi) system on the 996 3.4L too. Dollar for dollar I think either route will get you about the same thing either stock or modified, but swapping in a Porsche 911 engine should be much more straight forward.

Kirk

[kcpaz]

It's not just about horsepower. It's about ditching the M96, no matter the displacement. Go ahead and do the math and find out what it will cost you to build a 400rwhp "911" M96 engine vs. a 400rwhp Turbo Subaru engine, and then take a guess at which one will last longer and cost more to replace when it blows up.

I think you will have a hard time finding anyone who will be sympathetic towards ANY M96 engine when "better" alternatives are available.

You also have to remember, a lot of the people who would be interested in this sort of conversion are going to be at a crossroads where their Boxster already has a bad engine and they will be shopping for "more affordable" alternatives to tracking down another used M96.

A side note for your guys with good 2.5 motors. Wanna take a guess at how much your "good used" 2.5 engines are worth to the Boxster Spec guys? I bet you could fund a lot of the cost of the conversion by simply selling the existing motor.

[yimmy149]

I'm not knowledgeable on engine conversions. Would the original features of the car be preserved (PSM, ABS)? Seems like it would be challenging to get the Porsche gauge cluster to display info etc.

-james

[grantsfo]

I agree. Its a no brainer to go to far more flexible and better supported Subi powerplant. People who compare old 930 turbo lag to newer technology turbo 4 cylinders are in for rude awaking . These new turbo motors can be tuned to make power way down low and there is very little turbo lag. My little 2.3 Mazda turbo makes 275 Ft/lbs of torque at 2800 RPM. Many of the Subi tunes on the 2.5 motor are similar. Absolute torque monsters that would lay waste to a 3.4 M96 on the low end.

Let me see $3000 to $5000 for my used 2.5 M96 to a spec racer. Then $2500 to $3000 for a used 2.5 Subi turbo. Great tuner support for motors making upwards of 400 HP. 100 lbs lighter! Better weight distribution. Something else about M96. The m96 motors take for ever to spin up in events like AX. Subi motors spin up much more quickly. M96 is very expensive and experimental motor to turn into a race motor as well - no thanks!

turbo HO4 motor is what Boxster should have had when it was introduced!

[blue2000s]

Originally Posted by Kirk

I had an '02 WRX that I modded up to about 300 HP. That thing was fun to drift through corners when the turbo kicked it. I'm not sure how well this would work on the light RWD Boxster though. Isn't this the kind of behavior the original 911 Turbo had with the turbo boost coming on in a rush? That's why those things were widow makers and I suspect that's why Turbos are now AWD. A turbo Box with its mid-engine layout will be better than the old rear engine 911 Turbo, but you'd still run the potential for some extreme oversteer if the turbo hit hard while trying to power out of a corner.

I've been following this thread and personally I'd still opt for a 911 engine if my Boxster S engine failed. I can drop in a 3.4L 300 HP NA engine relatively easy. Compared to a stock STi engine you're pretty much even then. Sure you can mod the 2.5L WRX engine for more power, but you could also do a low pressure (6 psi) system on the 996 3.4L too. Dollar for dollar I think either route will get you about the same thing either stock or modified, but swapping in a Porsche 911 engine should be much more straight forward.

Kirk

I'd be really surprised if on a dollar for dollar basis you'd end up with an equivalent motor. I think the Subaru engines would be less expensive to purchase and keep up for an equivalent performance.

[kcpaz]

The thing with lag is there are SOOO many different turbo options available that you can basically fine tune the characteristics for your exact application. Grant is right, if you think it's going to be like 930 lag, it won't be... I mean it can be if you want it to be, but it doesn't have to be.

This prototype car for example...

2.5 liter motor
Stock cams
Dual ball bearing Garrett GT30R turbo with twin scroll housing

Horrible lag... I think not.

[grantsfo]

Originally Posted by kcpaz

The thing with lag is there are SOOO many different turbo options available that you can basically fine tune the characteristics for your exact application. Grant is right, if you think it's going to be like 930 lag, it won't be... I mean it can be if you want it to be, but it doesn't have to be.

This prototype car for example...

2.5 liter motor
Stock cams
Dual ball bearing Garrett GT30R turbo with twin scroll housing

Horrible lag... I think not.

Here is a 2600 lb 2.5 liter STI tuned for AX. Let me know if you see any lag here.

http://www.youtube.com/watch?v=hCl92i0O2zc&feature=channel
http://www.youtube.com/watch?v=YmXBHSVzGDA&feature=channel
http://www.youtube.com/watch?v=o3zNHhnWzL0

Now imagine that same motor in this 2000 lb Boxster. Oh I mean 1900 lb Boxster