10-20-2010, 01:50 PM
Hi guys. I started to build a 300 HP NA motor 3 years ago. I thought there would be a market in NASA racing in the GTS3 class. The HP matches up with typical lightweight 968 tub 2650lb to be at the top of the class. There are lots of BMW shops that make high HP E36 motors.
Goal was to use stock ignition and keep wet sump to keep cost down. Also by limiting power to 300 or so at 7k, reliability wouldn't be an issue.
My engine builder has run these at 335 HP@8k for over 100 race hours. BTW stock lifters and valve springs are used.
The engine has steel sleves, custom lightweight pistons 12.6:1 compression, special 2 piece cams with adjustable sprockets, Carillo Rods, cross drilled crank.
My total cost was close to 15K. When you start adding up all bearings,seals, belts, oil pump and all the stuff needed to build a fresh race motor, it adds up in a hurry.
Knowing the stock intake manifold was the limitation for more power over 6500 rpm was a problem. I had a custom log manifold made by Lance at Hayward in Vancouver.
We set up on SuperFlow engine dyno and broke in rings and bearings with sustained rpm tests. Breakin mineral oil was drained and racing oil with ZDDP was added.
First we tested with log manifold and large TB. As we tuned power kept climbing. We tuned 1000rpm at a time and worked our way up to 7k. Then we hit a wall. Engine wanted to keep going but rev limiter was kicking in. We tried several ways to raise rev limit or eliminate completely without success. best HP at 7300 was 317 . I was hoping for 335 at 7500. I wanted to put rev limit there. First day on dyno done $800 set-up $800 tuner and $800 dyno time.
Second day we didn't have any better results with log manifold so we put stock manifold back on and tried that...
Wow, we lost 15hp up top and added 25-30 from 4500 to 6300. Actually a good trade. A motor that makes 300HP at 6300. It will run forever.
After engine, manifold and testing I have close to 20K invested. Yikes!!!
There is more to be had by playing some more with Log manifold or possibly modifying stock manifold .
Pete
Goal was to use stock ignition and keep wet sump to keep cost down. Also by limiting power to 300 or so at 7k, reliability wouldn't be an issue.
My engine builder has run these at 335 HP@8k for over 100 race hours. BTW stock lifters and valve springs are used.
The engine has steel sleves, custom lightweight pistons 12.6:1 compression, special 2 piece cams with adjustable sprockets, Carillo Rods, cross drilled crank.
My total cost was close to 15K. When you start adding up all bearings,seals, belts, oil pump and all the stuff needed to build a fresh race motor, it adds up in a hurry.
Knowing the stock intake manifold was the limitation for more power over 6500 rpm was a problem. I had a custom log manifold made by Lance at Hayward in Vancouver.
We set up on SuperFlow engine dyno and broke in rings and bearings with sustained rpm tests. Breakin mineral oil was drained and racing oil with ZDDP was added.
First we tested with log manifold and large TB. As we tuned power kept climbing. We tuned 1000rpm at a time and worked our way up to 7k. Then we hit a wall. Engine wanted to keep going but rev limiter was kicking in. We tried several ways to raise rev limit or eliminate completely without success. best HP at 7300 was 317 . I was hoping for 335 at 7500. I wanted to put rev limit there. First day on dyno done $800 set-up $800 tuner and $800 dyno time.
Second day we didn't have any better results with log manifold so we put stock manifold back on and tried that...
Wow, we lost 15hp up top and added 25-30 from 4500 to 6300. Actually a good trade. A motor that makes 300HP at 6300. It will run forever.
After engine, manifold and testing I have close to 20K invested. Yikes!!!
There is more to be had by playing some more with Log manifold or possibly modifying stock manifold .
Pete
(This post was last modified: 10-20-2010, 02:31 PM by RS Barn.)
