Does anyone have any success in keeping their boost below 10 psi?

I am having boost creep problems. Here's my stats . . . I have a stage 1 rebuilt 89 turbo from BNR Supercars. It has a T04E compressor wheel, Ported wastegate, modified thrust bearing, and clipped turbine. Engine is a high compression (GSLSE rotor housings/rotors, and 12A side plates. Exhaust is straight through 3 inch mandrel bent, RB presilencer and Borla 3" straight-through muffler. Intake is a 50mm IDA style fuel injection throttle body. I was getting too much boost for my engines liking (~14-15 psi in 4th gear). The motor was pinging. I have big secondary injectors so I know the fuel is there (1650cc X2).

Last week, I pulled the turbo out and modified the wastegate and the wastegate exit. I cut a hole in the turbo backplate and welded a 2.25" pipe to where the wastegate flapper opens. This will allow the wastegate flapper to open more and it will also provide an easier path for the gases. I welded a divider to separate exhaust from wastegate exhaust. Check out the pictures to get a better understanding.







I am still getting boost that goes up to about 12psi in fourth gear at 6300rpm. I believe it would go up more but I let off the gas. The flapper can only as far as the actuator arm will allow. I am thinking that the wastegate ports which are supposedly ported within the turbine housing are not even ported at all. They don't look it.

I probably should have ported them out but I didn't think that I would need to. I thought the limiting factor would be the flapper door. I checked to make sure the actuator arm is allowing the flapper to open it all the way by disconnecting the actuator arm. This way the flapper is free to 'flap' all the way open. I will probably pull the turbo again and port these two holes out. But I am not too optimistic about the modifications success. I plan on adding water injection to my car but I would like to be able to control boost. Am I barking up the wrong tree here ands should I be looking at something else? It doesn't even seem like it is 'boost creep'. It just seems that the engine and setup flows too much to keep the boost down. Is this still considered boost creep. hmm, I don't know. I have heard of people putting restrictions in their exhaust but I don't think that is very efficient.

Any thoughts?
Thanks
DannyC

 

yes port and polish these two holes that should allow some mroe of the exhaust gases to excape quickly.. greats pics and work..we need more in depth pics like this so we can all see whats going on! try and and let us know!! p.s - more pics when your done

 

Sure as Hell looks like you know what you're doing. I'm pretty sure you're on the right track. Sounds like your engine flows very well and you just need a way to vent some of that excess exhaust gas. With where you're at now with the creeping and giving that great modification, I would think opening up those holes as much as possible just might do it.

On a sidenote with the detonation. What are you doing for an IC? Could intake temps be a factor?

I like the sound of your setup. What's your base compression ratio?

Cheers

 

I thank my friend Mike for hooking me up with information about this modification. I can't take the credit for the idea.

The compression ratio for a GSL-SE motor is 9.4 to one.

My intercooler is a modified Starion on. I don't think that the temps are a problem. It's the winter now and I am getting intake temps of around 10 degrees celcius and lower. As soon as the winter hit, boost started creeping and I blew my motor. I cracked the rear housing- I believe due to detonation.

Thanks

 

Since you're good at welding you could go really big with those holes, maybe join the two to make a big oval, and then put a new flapper on it. Maybe there are things I'm not thinking of like the structural integrity with it like that or something. I'm trying to think of the reasoning behind the two holes, and them being different sizes. (thanks for that great pic, I was so busy putting mine in I never took any) It's probably just that there was more room for the bigger one.

External wastegates get pricey but with what you've done to your turbine housing you could add one pretty easily. I don't think it will be necessary after some more porting.

Cheers

 

LOL. Its funny you say, 'my great welding'. If you only saw how I welded. I brought this to a shop to weld after I attempted to weld it.

I always wondered why they have two different size ports. It doesn't seem to make much sense. Each port is for an individual rotor, right? So wouldn't you want each rotor to 'waste' the same amount of energy? Maybe one has better flow characteristics and therefore they even out? I dunno.

I will be porting out the the housing again and I will be putting up more pics of what I have done. We'll see.

 

I forgot about it being divided. Duh, there's the reason for two holes. Now why different sizes?

Looking forward to hearing how it turns out.

I just wish I had my own welders, and a lot of other equipment.

Cheers

 

Gald to hear everyone likes the seperated wastegate / tube idea. I was going to run this when I was planning on running a hybrid, but I elected to go full T04E . Hopefully porting the hell out of those wastegate holes does the trick.

~Mike.......

 

I pulled the turbo out again to port the wastegate holes. The hole size when I started was 20mm and 23mm. I guess BNR didn't port these things at all! I am very disappointed in him.

I opened them up to 25mm and 28mm. (The max size that the plunger will cover is 26mm & 30mm). So now the total area is around 11mm^2, which is a little bigger than a 35mm wastegate. I also tapered the entrances of the ports to allow easier flow of the 'wastegated' gases. see the picture below with the circles.

Now the results . . . I took it out for a spin on Saturday. It was a very cold day. My intake temps were ~7 deg celsius. The recipe for boost creep was there. For some reason my WOLF computer always registers ~2psi higher than my Autometer boost gauge. I have heard of this from other people too, so I usually try to go by the Autometer Gauge. I have no clue why it does this. Ok, now here's what I found.

In 1st and 2nd gear my Wolf3D computer said it didnt go past ~6.5psi. I am not sure of the exact numbers, besides 1st and 2nd gear weren't my problem.

In third gear I did get it to go up to 9.9 psi(as per the WOLF) at ~7200RPM, which should only equal ~7.9psi in real life.

In fourth gear at around 6500rpm I only got the boost up to 7.2 on the WOLF, which would mean that I am only getting around 5-6 lbs of boost, NICE! I ran this a couple times wit hthe same results. I was on the highway and it was weird to see the way the boost climbed up & just stayed there, at 5psi. I guess I am just not used to it.

I think I will need to make some more trial runs to see how consistant it will be. This is a huge improvement from what I was getting before (~14 to 15psi).







Danny

 

Saweet, very sweet, glad you got the problem worked out and I could be of some help !

~Mike.......

 

i saw those pix. i didn't know it was your car. it looks very interesting. just about everyone running stock TII turbo has boost control problems. i know i did.... the sky was the limit then BOOM! i caution people alot when putting on full exhausts. the work looks great but i think its a bit overkill for all the time and money an HKS T04E kit is around $2200 isn't it ?

 

Thanks for all the help, especially Mike.

 

The money I spent on this turbo vs a T04+manifold+wastegate is a lot less than $2200. The wastegate mod only cost me 30 bucks and that's because I can't weld. A T04 is nice but it doesnt fit my budget right now. If I upgrade the turbo then a list of other things will need to be upgraded as well (ie: engine).

 

i just love how well external wastegates control boost

 

Dude,

Nice work, I must admit that your engine setup looks awesome (at least to me). That is exactly what I want, well maybe with a Holley style EFI carb, but still!! Did you dyno your car without the turbo?

Keep up the good work

 

Thanks! Sometimes I wonder if it's worth all the work because it gets a litte out of hand and I spend more time tuning and working on it than driving. I can say that I do like working on it.

I haven't dyno'ed the car since it was 6-port and had a Dellorto. I would like to hit the dyno and tune it this spring.

 

That's EXACTLY what is all about That's what I call FUN

How much did you dyno with the 6port and Dellorto?

 

126 max hp, I forgot at what. It was maybe 3-4 years ago. It was ported too. Now you see why I went turbo. More Power!

 

Nice work

 

126HP max?.... Street ported?.... something was definately wrong there! My street ported 13B 4 port with a Weber 48 IDA hit 181 RWHP (over a year)with no tuning. I'm confident that with proper tuning and no further engine modifications (other then timing) I could hit 200HP or come damn close to it.

-Rich

 

181 RWHP translates to about 208-217 hp which is damn good. I know 4-ports make more power than 6-port motors but thats a big difference. The other guy who was there has a street ported 6-port GSL-SE with the stock throttle body, AFM, etc was putting down the same.

 

FYI more pics of the project posted here :

http://www.dcee.rotarymaniacs.com/tu...turbopics.html

Info posted here:
http://www.dcee.rotarymaniacs.com/turbo7/turbo7.html

 

dc i think i am gonna organize a dyno day. shoot me a pm if you are interested

 

Hey DC I'd like to get a ready-made down pipe like yours, can you help a brotha' out?

-Rich

 

Just an idea but would it also help if you wrapped your pipes in exhaust wrap to keep the temps up and the flow faster?

By the way that is simply amazing. I wish I had the time and facitlities to play like you do

James