TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Hey Guys...

I've completed my D16Z6 rebuild about 3 weeks ago, and I'm using a custom Turbo Cam (for 9PSI), 5-angle valves, a 10:1 FMU, 1 step colder NGK spark plugs, stock injectors, stock pistons and stock rods.

I've been running this setup with an IHI RHB5 turbo for about two weeks now, without any problems, pinging, detonation, etc... The max boost in 5th gear hit 9PSI, but most of the time it was about 7-8 PSI.

Yesterday I've changed an elbow, that goes from the turbo to the IC from a PVC (very restrictive) elbow, to a nice flowing welded elbow... The new elbow is a lot less restrictive, the turbo spools up VERY fast, BUT:
here's the problem...... !
I'm boosting at like 12 PSI max, and an average of 10 - 11 PSI.....
Do you guys think that this might be too much for a stock (but freshly rebuilt) D16Z6 ('95 Si).
The car feels so ------' fast, that it's scary, but I don't wanna blow up the freshly rebuilt motor. ???
Aha, and I've heard no detonation, even with these HIGH PSI's.

How much boost should I be running?
What would be a safe PSI setting for my motor with the parts that I've mentioned at the top?

How come the elbow made such a HUGE difference in boost? (from 7-9 PSI to 11-12 PSI).

What's the best way to lower the boost on an IHI? (The guy who was rebuilding my turbo suggests putting washers underneath the wastegate, where it connects to the compressor housing. Is that a good way?

Thanks in advance for all the answers.

P.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

as long as you are not leaning out, 10 psi is fine. a local guy up here has a boosted d16y8 running 10 psi and a little over 200 HP to the wheels. you should be fine at 10...12 is really pushing it. use a bleeder valve to control that boost

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

A bleeder vavle will increase the boost. As long as you have enough fuel the 12psi should also be ok. You looking at 120psi fuel pressure at that level and its not going to be long till the pump or injectors start to have problems.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Please explain how a "Bleeder Valve" works, and where I can get one... Do you have any pics of where it goes?
Thanks.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

a bleeder valve goes in the line to the wastegate actuator. it bleeds the boost pressure off so that the wastegate opens later.. This increases the boost. you can get all the parts at homedepot for about $7

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

OK, so a bleeder valve INCREASES boost...
What should I do to DECREASE boost?
(can this be done with a bleeder valve?)

or... Do I have to take off the turbo off the mani, and modify the wastegate actuator arm? (Is there any better/simpler/faster way of modifying the boost setting on an IHI RHB5?)

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Lenghtening the arm is the only way I know of.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

How much do I have to shorten it by (approximately) to land in the 8 PSI range?
Do you know of a place where I can find pics of a "modified" wastegate actuator arm (instead of a shitty-ass diagram in the NEWBIE FAQ's...? (I wanna see what parts I need to get in order to lenghten/adjust it...)

Does anybody know exactly what parts I need to get in order to do this?

(IS 12 PSI too much?)

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

I don't think 12 psi is too much with a good fuel system.. it is a little high with an fmu.

www.denverspeed.com has a good write up on the actuator rods. I think you need to make it longer. doesn't it push the wastegate flapper open?

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

the FAQ has a few topics on this.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Hey, thanks a lot for that link...
I'm just wondering what the guy is using the SPRING for on the wastegate?
(Does it HAVE to be used? Why?)

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Ok..

Instead of just making the rod longer so that it doesn't shut all the way. He puts the spring in and them preloads the actuator. You can see in his write up that it actually moves the rod with less pressure. He maintains the same rod length but the spring acts like constant boost on the actuator.. You tighten it up as much as need to get the desired boost level.

Ken, the owner of the site, is a really nice guy. If you have more questions just email him. He has good deals on EGT meters also.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Hmm.....

I feel RETARDED :o

Although you've explained the point of using the spring, I still don't get it (maybe I'm just tired).

Please ELABORATE on why he used the Spring...
What would happen I didn't use a spring...
Different boost level?
Different boost CURVE?
(or just a major -----up, because the wastegate won't close?????)

Do I NEED to use a spring?

(sorry to bug you, but I wanna get this right).

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

lol peter.. never ending huh...

go back to the pvc elbow ;) j/k

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

spiking to 12 should be ok as long as your not detonating. but i would get better fuel management. lates.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Ok.. the difference between spring and no spring. First no spring. The no spring method is to lengthen the rod so that when the actuator see's 10 psi its not pushing the rod farther open and letting more exhaust out. Thus keeping boost lower. The downside is the wastegate is always a little bit open.

With the spring method you adjust the wastegate rod to the original length so the flap stays shut. Here is the easiest way I can explain what the spring does. You have a seesaw, like in a play ground for kids. I weight 200lbs and you weigh 100lbs. To make it work someone else would have to push 100lbs on your side.. That someone is the boost in our case.

So at this point your at 100lbs boost.. Say you only want to use 80lbs boost. you would have to hold a 20lb weight. Then it would only take the 80lbs since your already preloading yourside with the weight.

Now.. Since boost pushes on the back side of the actuator housing and forces the rod out, and this takes 12psi in this case. you do all the mods on his site. What the spring does is push on the two washers and preload the diaphram inside the actuator. You put more preload on the spring to decrease the boost and take it off to bring it back to stock. I'm not sure what size spring and the exact tension you need. That will be trial and error.

So the spring will allow you to keep the wastegate shut like normal by applying a preload to the wastegate rod. Make sense now? ;D

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

oooh i get that now.. good explanation...

you get a spring that more or less simulates 4psi of boost (example). then the turbo would push open the 12psi wg arm at 8psi instead of 12.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

yeah exactly. and you adjust how much you push on the spring by the threads on the rod. You sqeeze it more for lower boost.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Todd,

Thanks a LOT for that explanation...
(Now that I understand how it works, I feel like a dumbass for asking you such stupid questions.)

As you can see, Physics is not my Major :)

How reliable is this method of boost adjustment?
Does Pre-Loading the wastegate with the tension of the spring cause any LAG, does it cause the turbo to SPOOL UP FASTER, or it makes no difference on the spool-up time...

(uh oh... I feel like I've just asked another dumb question.)

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

it will be just as reliable as stock..

your boost response will be the same as it was stock, assuming you get the rod length the same as it was before.. its important to measure twice before you cut the rod the first time.

Another nice thing about this is when your ready for higher boost you just use the main coupler and make the rod shorter. This will make the diaphram push harder to open it and increase the boost.. Saves you $7 on a needle valve.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Ok,
thanks for all the info...

What do you suggest I should be running with the setup that I've mentioned above... (stock fuel pump, FMU, colder plugs, stock pistons, rods)?

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

I would try to keep fuel pressure below 80psi.. That should be around 8psi boost with that 10:1 fmu. And I would upgrade the fuel pump.. Thats just for saftey. Once you go to bigger injectors and an uberchip I say 10-11 should be no problem. I know a few guys locally that run 12 daily and for a while the one was at 16.. He turned it down though.

I know you had it higher before but running more than 80psi fuel pressure is asking for problems.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Ok, thanks for the advice...

What fuel pump should I get?

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

One made for high pressure. Either the hi pressure 255lb walboro or one of the inlines designed for high pressure. Most of those are only made for 60-70 psi though. Really if you wanna run high boost I would look into getting a chip and injectors. Joseph can probably hook you up for about $200 Then you can keep the stock fuel pump.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

$200 for the chip and the 450cc injectors?

So if I get the 450cc injectors, and the "chip" (a modified ECU chip, I assume), I won't need to buy an AFC to control the bigger injectors?

Does the chip have a modified fuel map?
Different fuel ratios at different REVs?

How do you change the chip?
Do you need any special tools? (links ?)

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

yep $200 for a set of injectors and the chip.

Look in the engine management section, Joseph is the mod there. The chip works with your stock ecu, you solder a socket in so it can be removed for retuning. he can do that if you can't. The chip works with boost and he can remap your fuel and ignition tables. Normally he puts in .5 degree timing retard per psi of boost. it has a launch control as well as vtec point. Drop him a line to find out about total cost including soldering the ecu. If you pay shipping both ways he will probably to it all for $200.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Uh... all this camotion, how bout getting a ...BOOST CONTROLLER!!!! ::) Makes sense to me... ;)

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

A boost controller for a turbo with an INTERNAL WASTEGATE?
Where can I get such a controller, and how much do I have to spend?

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

first of all your car is never going to detonate...so dont be looking for it. This is caused by an excess amount of fuel and im SURE you are running lean, very dangerous. You need bigger injectors and a VAFC or hondata, I didnt read the post so if you already have one of the two sorry. Anywho, the DSM injectors are good but now rookie friendly. I would just suggest doing the smart thing and everybody in here is going to hate me for saying this, but dont be ------- cheap, go out and buy some nice RC 310 or bigger injectors and save yourself the grief and time, after all it is your engine.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

no. be cheap and get the 450s and then send them to rc and get them balanced and cleaned for like a $100. ;D

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

A boost controller will only increase your boost pressure above what the factory setting is.

The dsm 450cc injectors are perfect and very rookie freindly.. Why would you say they are not? if you get a set that is dirty then clean them.. or send them off and have them cleaned.. Joseph cleans his in an ultrasonic cleaner before he sends them out. They work perfect with his chips.

And you can detonate when its lean. The boost pressure can make the fuel that is there ignite before the spark.. Thats detonation and any amount of fuel will do that.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

So then how do you tell if too much boost is too much. If pinging can be when your too rich? And how do you know exactly what is right?

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

Your motor will blow up...

There are enough turbo hondas that you should be able to tell from what other people are running where the maximum safe boost level is. If you don't run enough fuel you WILL detonate and blow it up. That is the most important part. Next is timing.

For most cars 6-8psi is safe. Anything above that you want a good fuel system. Talk to some guys with the same engine as you and see what they are running.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

So once again, Joseph, the moderator from the "engine management" forum sells the chips and cleaned injectors for $200? Do you know where he's located?

How much boost could I safely run with such a setup?

Will my car pass emissions with the bigger injectors and the chip?

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

yeah Joseph Davis is his name he is in NC. You car will run clean once you have a good tune on it. Just like stock. your map sensor will read boost up to around 10-11. I don't know for sure how much boost the z6 will handle. I would imagine right around there. Send him a PM and he will hook you up with everything you need. He can also explain things alot better than I can.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

lol peter, getting into programmable engine management.

your simple little boost plan on a budget idea is more then you thought it would be huuh. lol...

It NEVER ends does it.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

He can sell the missing link and fmu for what the chip and injectors will cost. The simple plan ends as soon as you feel the boost and decide you want more.. ;D

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

I thought Joseph worked with Ghettodyne not uberteg.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

He does both. most of what he did before was obd0 now he is getting more into the obd1 stuff.

Re:TOO MUCH BOOST? (On my D16Z6 with IHI RHB5)
 

ahhh i see... well thats good news for 5g people!