Full Boost?

[Artie]

How do your boost patterns go? On acceleration in 3rd gear at 3K rpm and wide open throttle(with WC chip) I get 1.25bar initially then drops down to 1.05bar then climbs back up to 1.1bar ish. Is this normal boost for a high boost chip and WC turbo? I can't seem to get the boost to remain steady. Weird, on other turbo cars I've worked on RX7's, Supras, Eclipse/Talon's you get a certain boost and it holds that boost til redline. I've put an electronic boost controller on the car and it's more consistent than it was with the solenoid hooked up but still hit's 1.25, drops off then climbs back up. Anyone else experience this?

Artie

[CarlC]

Hi Art,

My car did exactly this for a long time and I spent months testing and tracking down the cause which for me were numerous. My car now boosts fully and holds steady to red line as you expect. Main causes for me were knackered wastegate actuator and boost solenoid valve. When testing both these they appeared to be working correctly. In the end I replaced them anyway and that pretty much solved my boost problems.

Your cars looking fantastic and those engine mods look superb! Be great to see some performance number once you have your boost issues sorted.

[Artie]

Hi Art,

My car did exactly this for a long time and I spent months testing and tracking down the cause which for me were numerous. My car now boosts fully and holds steady to red line as you expect. Main causes for me were knackered wastegate actuator and boost solenoid valve. When testing both these they appeared to be working correctly. In the end I replaced them anyway and that pretty much solved my boost problems.

Your cars looking fantastic and those engine mods look superb! Be great to see some performance number once you have your boost issues sorted.

Carl,

Well, I can say that my boost solenoid isn't causing the problem as I am using my electronic boost controller. I am beginning to think my turbo is just not efficient enough to provide boost consistently at the levels I have had set by my chip. Although I am supposed to have a WC stage 1 turbo, I bought if from a local shop known to stretch the truth. Anyway, if it clears up today I am going to try a few different settings on my controller to hopefully cure the problem.

Thanks for the compliments! I am happy with the body mods I've done thus far, thinking to add the S300 wheel arch extensions to complete the package(as I am still waiting on my SE sills). Well, if I could get the boost to hold steady, I would expect about 30 more HP to the wheels. I dyno'd last week and she put down 273 hp at the wheels and 274 torque. I wasn't maintaining boost already but on the dyno, she wouldn't get boost above 1.1bar and it would drop to .85/.95 ish.

Artie

[Artie]

Anyone monitor their boost patterns? I'm suspecting I'm getting overboost then drops off to max boost. John Welch suggested I do a compression check, which I did a few months back, but will do again. He also suggests that it could be restriction in the exhaust. I'll check compression first then report.

Artie

Carl,

Well, I can say that my boost solenoid isn't causing the problem as I am using my electronic boost controller. I am beginning to think my turbo is just not efficient enough to provide boost consistently at the levels I have had set by my chip. Although I am supposed to have a WC stage 1 turbo, I bought if from a local shop known to stretch the truth. Anyway, if it clears up today I am going to try a few different settings on my controller to hopefully cure the problem.

Thanks for the compliments! I am happy with the body mods I've done thus far, thinking to add the S300 wheel arch extensions to complete the package(as I am still waiting on my SE sills). Well, if I could get the boost to hold steady, I would expect about 30 more HP to the wheels. I dyno'd last week and she put down 273 hp at the wheels and 274 torque. I wasn't maintaining boost already but on the dyno, she wouldn't get boost above 1.1bar and it would drop to .85/.95 ish.

Artie

[Vulcan Grey]

I haven't driven my car in so long I can't remember...

I think I remember, when everything was running well, and at my high altitude, and using the stock SE memcal, I could peg the boost needle all the way up a long hill...

The freescan logs would show 2.24bar often, never saw it taper off rapidly like some say.

The I got a couple of chips from Sanj, S4s stumble reduced, and the #4. I've tried the first one, and the boost builds much faster than the SE chip, but by then my chargecooler impeller was dead, and I was soon overboosting and cutting out.

of course the effects of my 5300ft + altitude tend to skew the boost levels a bit...

[rens914]

I have the same problem at the moment

super 60 turbo and #6 chip

worked fine before

no full boost any more ( after a few secs full boost)

checked a lot but dont have a freescan cable yet

i do have the thought that my wastegate or boost cellunoid is causing the problem

going to have it checked next week

let me know if you find something first

gr rens

[docf]

Anyone monitor their boost patterns? I'm suspecting I'm getting overboost then drops off to max boost. John Welch suggested I do a compression check, which I did a few months back, but will do again. He also suggests that it could be restriction in the exhaust. I'll check compression first then report.

Artie

I dont know the specs on the WC turbo but I have a T3 super 60 with a #2 chip and a blitz boost controller and I can hold 17 psi like a stone from 2500 rpm to redline. The wastegate actuator is a good place to start.. tighten it up enough so you get ~9psi with no boost controller just a boost source connected to the actuator and then see if that makes a difference once you button everything back up. If you were hitting the 18psi limiter it would be a little more violent then just a gradual dropoff in boost so that sounds unlikely. You should also check for boost and exhaust leaks but again.. unlikely given the facts.

[pitstoppete]

this interests me too folks, have had three years playing with my set up, so my 2p worth-

i'm getting 1.24/1.25 bar every time i ask for it with my St 1 WC ceramic one. with the old std turbo i used to get 1.25 still, (once id fixed the chargecooling) but it soon tailed off to less than 1 with real high MAT climbing too. then down to 0.65 (on the wastegate) when it was really hot.

As u probably know the chargecooler system has to be really good to keep the MAT down. (mine was seized, the pump, and the cooler pipes were solid with crud, as were the hoses and rad. 8 hours pumped round with a mixture of vinegar and bog descaler seemed to work well! leccy pump is a must it seems. i can see why the std is there, but an electric seems a better idea.

biggest difference to mine was when i made a 3" exhaust for it. it really changed the grunt delivery of the engine and of course it now sounds like it looks.....my neighbours hate me though. popping and banging with flames is not too social apparently. I hated the quality of the after market "stainless steel" rusty one i had, so made a flange adapter, bought 3" jetex parts from Merlin Motorsport and made my own. its a bit lairy. but it was about 90

Edited June 12, 2007 by pitstoppete

[Artie]

I'll try the wastegate actuator trick first. I did a compression check tonight and at my 1023ft. above sea level I registered as follows, engine warmed (and subsequently cooled back to 66C), throttle plates open:

Cyl 1: 150psi

Cyl 2: 152psi

Cyl 3: 152psi

Cyl 4: 155psi

All within spec(minimum of 140psi at sea level). I'll look at addressing the exhaust restriction which I think could possibly be the case. I have a fairly small 2.25" diameter(stock pipe size) stainless downpipe(decat pipe) with a stainless magnaflow 2pass muffler(both outlet and inlet in the same side)

I'm looking into 3" exhaust downpipe and 3" twin input and single outlet muffler so I can do dual outlets!

Art