308 Turbo Mod

Hey everyone... I thought I would take a couple minutes and post up some info on a project a buddy and I have been working on. We both have 308 QV's his is a 1983 and mine is a 1984. For the past year or so when ever we get together it seems we always end up on the "How can we got more performance out of our cars" conversation. We have both been following the many supercharger threads and we have been very impressed with the results. Mark and Scott have both done fantastic jobs with there supercharger installs and I want to thank them for posting up a lot of very good technical information!

So a few months we decided to get serious about adding some power to our cars. Our goal was to try and get 300HP at the wheels with out making ANY permanent modifications to our cars. (I don't plan on selling mine... but you never know.) We also did not want to spend $10,000. Our first thought was using a supercharger. Again our goal we to use the stock fuel injection, air box, intake manifold, ignition... ... you get the picture.

After reading the many threads we decided on using a Eaton M90. I was able to get one for $400 off E-Bay.. We were ready to start... all we needed to do was make some mounting brackets, a couple pulleys, some intake tubing, and we would be set. Once we got the unit in our hands we realized it was a bit larger then we hoped it would be. We tried mounting it in many places but could not find a place that did not require modification. We determined that if aftermarket engine management was used a great place to mount it would be where the stock fuel injection is located. We looked into a centrifugal supercharger but they were a bit too expensive. (over $1,500)

We took a step back and thought about other options. We decided to try a turbo.. the mighty F40 uses them so they can't be all that bad. I have had some experience with turbos on my S4 so I set about doing all the calculations to determine what size turbine and compressor we would need. For our first attempt we went with a single Garrett turbo (T3/T4 hybrid). After calling a bunch of turbo specialty shops I was able to find what we needed. (On a side note it is scary just how much some of the self proclaimed experts don't know) Using a turbo did require us to get 2 extra parts: wastegate, by-pass valve (we used on off F40). Exhaust was one thing we knew we would have to modify. However it did not have to be a permanent change!

The exhaust ended up being more of a pain then we thought it would. In order to mount the turbo where we wanted to we realized that the stock rear header could not be used. So we fabricated a new rear header and exhaust. To get the turbo system installed did require some modification but none if the changes are permanent. We did not damage any of the stock parts. Well except the one I backed over

To make a long story short we then mounted the wastegate and the by-pass valve, installed O2 and Boost sensors, and ran the turbo oil lines. For the oil return we did NOT have to drill and tap the block. 2 weeks ago we got her running... that was a good day for me because we were using my car as the ginny pig Im just glad to get it running again!!

Last friday we made a trip to the dyno. The runs are pictured below. My car has a completely stock motor that has 45,ooo miles on it. I had a major service done before we installed the turbo. Our wastegate is set to run 8 psi of boost. However once and a while at around 7000 rpm we see 9psi on the boost meter. We did a couple pulls on the dyno. The best run was 305hp / 262 ft-lbs and the worst run was 303hp / 262 ft-lbs at the wheels. The Air/Fuel ratio looked pretty good. It fluctuated between 11.5 and 13.5.

We have put a lot of miles on it and everything is looking good so far. It really pulls hard. Made a big difference!! We are very happy with how it turned out.
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Mark - I am out of town till next week. When I get back I will send you the turbo information. The timing is stock. I thought we might run into a little timing issue but with the low boost and properly sized compressor we are not having any detonation issues.


Aaron - We would love to meet up with you sometime. If you have some free time over the holidays let me know and we can set up a time to meet. We look forward to it.


chiprich - We have given some thought to direct fire ignition but so far the stock units are working great.

 

Yes, we tried very hard to keep the budget as low as possible. For all the parts I think we have around $3500 invested. However the big cost was in time. We have many many months invested in research, design, fabrication and testing. Very enjoyable hours though As for a kit... well we really have not thought about it. If we got a couple people who were interested it would be worth looking into.

I am out of town this week. When I get back I will post the calculations we used to size the turbo. As for lag... we are not seeing much lag. The turbo starts to spool around 2500 rpm and you can feel the boost at 3000 rpm. It pull real hard all the way to red line. And as for smog we are in Ohio and do not have testing here. However I beleave this setup can be used with the stock exhaust. Might loose a bit of HP though.

 

For a muffer system we are using a polished SS Magnaflow muffler and polished SS tips. However, the stock system should work too. Of course it will not flow as well

 

We used a Garrett T3/T4 with a 60 trim TO4E wheel and .81 AR. On the turbine side we used a .82 AR with a 4 bolt standard turbine discharge. However this created a very large lag. The turbo did not start to make boost until 4000 rpm. So we switched to a .63 AR and it now starts spooling up at around 2500 rpm. It spools up very fast!

We did not run into any Ferrarri specific issues. The 308 is a very good candidate for a turbo or SC. As for how we picked the turbo... First we did a ton of research on turbocharging theory, sizing, maps, and equations. I am putting together some detailed information. I should have it complete in a couple days.

Here are a couple more pictures of the prototype single turbo.
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I will get some pictures of the K-jetronic adaptor this weekend.