jskarateka
Member
- Joined
- Nov 16, 2008
I've been focusing on tuning for years but I seem to have a lot of exhaust backpressure that I believe is hurting my 1/4 mile times (11.9-12.2 @ around 110-112mph 1.7-1.8 60ft) . Had the problem with my stock unopened block and heads, but it got worse with the new engine build.
I have to plumb my regulator type boost controller as shown in the attached picture, to hold the wastegate closed so that I can get 25 or more pounds. With it plumbed the correct way, back pressure will open the wastegate.
With the regulator plumbed the correct way on the old stock long block (and all my current bolt-ons) the most I could get was about 20-21lbs at the beginning of the run, with some creep to about 23-25lbs at the end.
With the regulator plumbed the correct way on the new block/heads/cam it was worse when I tried it. 17-18lbs max at the beginning of the run with creep to maybe 21lbs.
If I plumb it like the picture, I can adjust the regulator for whatever boost I want over 20lbs, and it will spool fast to that amount and hold steady throughout the run.
Nothing appears to be wrong with the tune or exhaust or otherwise. Opening the dump does not help.
Does that sound like I'm getting way too much back pressure? Any thoughts on the best way to correct?
Too small turbo maybe? I got the TA49 turbo before I had the new long-block build (blew a rod bearing on the old block). As I stated above though, even then I had the issue to a lesser degree.
I have to plumb my regulator type boost controller as shown in the attached picture, to hold the wastegate closed so that I can get 25 or more pounds. With it plumbed the correct way, back pressure will open the wastegate.
With the regulator plumbed the correct way on the old stock long block (and all my current bolt-ons) the most I could get was about 20-21lbs at the beginning of the run, with some creep to about 23-25lbs at the end.
With the regulator plumbed the correct way on the new block/heads/cam it was worse when I tried it. 17-18lbs max at the beginning of the run with creep to maybe 21lbs.
If I plumb it like the picture, I can adjust the regulator for whatever boost I want over 20lbs, and it will spool fast to that amount and hold steady throughout the run.
Nothing appears to be wrong with the tune or exhaust or otherwise. Opening the dump does not help.
Does that sound like I'm getting way too much back pressure? Any thoughts on the best way to correct?
Too small turbo maybe? I got the TA49 turbo before I had the new long-block build (blew a rod bearing on the old block). As I stated above though, even then I had the issue to a lesser degree.