My Holset Build (Big picks)

[rcrdps]

I'm not the original poster, but um:

No, it's not really a problem. You're just limited on how much boost you can run. Your MAF does the normal calculation of how much air is flowing, and adjusts fuel accordingly. Your stock ECU is set to around 10:1 AFR at redline. Whether you run 2psi or 20psi, it's going to try to keep it at 10:1. Of course, it can't at 20psi and stock injectors. So you can run your boost up until you're maxing the injectors. In the case of this bigger turbo flowing more air even at lower psi, you might have to run lower psi than stock, but you'll still make more hp because the engine breaths better on the exhaust side, and the compressor doesn't heat the air quite as much.

So he's only set at 8psi, but he's making more HP than I am at 14psi on the stock turbo just because he has a more efficient pump.

Gene

[Nissan2367]

^Correct^ You dont "need" those upgrades just because its a bigger turbo but you have a limit on how much boost you can run. I am only at the stock 7-8psi so i am safe. And yes i do have a wideband... your stupid if you dont run one on a turbo car!

The manifold is cast steel so it can be welded but you need to follow a prosses. I heated it up with a torch until my hand was about a foot away and i could feel the heat coming off of it. Then I used a 220 welder on max to weld it. I have a friend that did this on a HX honda manifold and has never cracked or broke and he is going on 3+ years of use! I know there is another way to do it but a normal wire feed will not work. You need to make sure the manifold is hot because they are made to absorb heat so if you weld on it and dont have it hot aleady it will cause a bad brittle weld.

Good luck, Its fun to drive! Holset's are awesome!

[Nissan2367]

are you sure that stock header isnt it galvanized?.and arent those plates metal?.how are they supost to stick, even though it sticks after a while wont it brake off??.

or i might be wrong

Galvanized is just a coating... I have welded steel, ss, and mild steel all together before its not a huge deal and it all welds together... Not the best to do but it works. But its galvanized anyway.

[rcrdps]

[QUOTE=Nissan2367The manifold is cast steel [/QUOTE]

That's good to know. I was afraid it was cast iron.

I gave my 220arc away. Guess I'll use my oxy/acetelene if I decide to weld the flanges on.

Gene

[meet07]

stock manifolds are cast iron....last time I checked

[Nissan2367]

Not really sure... Oh well welded like butter!

[wrgibson]

I'm not the original poster, but um:

Your stock ECU is set to around 10:1 AFR at redline. Whether you run 2psi or 20psi, it's going to try to keep it at 10:1. Of course, it can't at 20psi and stock injectors. So you can run your boost up until you're maxing the injectors. In the case of this bigger turbo flowing more air even at lower psi, you might have to run lower psi than stock, but you'll still make more hp because the engine breaths better on the exhaust side, and the compressor doesn't heat the air quite as much.

Gene

Is this true in regards to an RB20 ECU? I'm putting the HY on a 20 and was going to make the stock rb turbo's wastegate actuator fit the holset......hopefully. That means 10-11psi. Can my ecu "learn" to handle the increased flow from the HY at 11psi?

endthreadjack:

[Cjmartz2k]

No

[Nissan2367]

Hahaha Quick and right to the point! Good luck trying to get that internal gate to fit... just upgrade to the external gate!

[rcrdps]

No

Please do elaborate. Are you saying the ECU won't try to compensate, or are you saying 11psi will max the injectors? I aggree with the later. But the ECU will try to get there until it maxes the injectors or the MAF. I wouldn't say it's "learning" anything. Just compensating.

Gene

[wrgibson]

Good luck trying to get that internal gate to fit... just upgrade to the external gate!

I've got a friend who already made the internal gate from a Saab fit his HY....I don't see him having any problems with mine. Once he's done maybe I'll post up some pics of it or something.

Also, I'm with Gene. Cjmartz2k, please elaborate.

[rcrdps]

I'm going to try the internal gate. I ordered a WGA off ebay and welded an angle bracket to the turbine housing:



Gene

[Nissan2367]

Interesting... I stand corrected. I just hate internal gates. They creep all the time and are just not accurate. Good luck and keep us posted on how that works out!

[rcrdps]

Yeah, I'm worried about creep. We'll see. My spacers don't have the divider though, so that may help equalize the runners and make the wastegate more effective. It will probably increase spool time though. Time will tell.

Gene

[Cjmartz2k]

What I was saying is you can't just put a bigger turbo on and expect it to run right, even with in the limits of the MAF. If that were true, all anybody would need for under 500hp is a Z32 MAF and a SAFC to tell the stock computer how to read the Z32. He'll need a re-tune.

I also think the OP is confused on how ECU's "learn" things. They aren't some magical box that learn the mods you make over time, and need to be reset every 5 minutes by disconnecting the battery and stepping on the brake, which will also solve 90% of your problems (if you read the australian sites a lot that is). RB20 ECU's do make a good base for ROM tuning though.

[wrgibson]

Thanks for the info cjmartz. That was the impression I got when researching how to get my holset on there.

[rcrdps]

[QUOTE=Cjmartz2k]What I was saying is you can't just put a bigger turbo on and expect it to run right, even with in the limits of the MAF. If that were true, all anybody would need for under 500hp is a Z32 MAF and a SAFC to tell the stock computer how to read the Z32. He'll need a re-tune. QUOTE]

Maybe I'm not reading you right. Or maybe I don't understand how the questions are being asked. So I'm just going to explain how I see it in a little more detail.

The only thing you really left out of the equation for 500hp is injectors. I don't fully know the SAFC abilities, so I don't know if it can compensate for larger injectors. So we'll assume you keep the stock injectors. Your theoretical max hp is going to be around 280hp.

The ecu is smart, and a MAF system is very forgiving. A MAP system is not forgiving. But the RB ECU's are MAF. I forget the stock MAF maximum air/flow. If it's lower than 280, then that's your bottleneck. We'll assume for now that the injectors are the limit. Your MAF detects the airflow up to it's limit. The ECU looks at it's map, which is determined by your load( actually VE, but load is easier to think in), and calculates the fuel needed to hit a certain AFR. Then it fires the injectors to feed that much fuel. For the most part, when you come on boost, your ECU sees that as a max load for that RPM, so it uses last number on that list. I stated before that it was about 10:1 at redline, but I looked and the theoretical number is more like 10.5:1 AFR. Mine tends to run a little leaner than the theoretical number. So lets assume you have a stock turbo. At redline, the MAF sees some airflow, and the ecu calculates the right fuel for 10.5:1 AFR. If you have a bigger turbo: The MAF sees more air, and the ECU calculates the right fuel to make that volume of air a 10.5:1 AFR.

If you stay within the limit of your injectors and MAF, then yes, your bigger turbo will run fine. Obviously, you should have some way of checking your AFR to make sure you are in the limits.

Now of course, a tune is recommended. But what's a tune? Usually they leave the ignition basically stock, and they raise the AFR to closer to 12:1. If you tell them you're going to run mack-daddy boost, then they might pull timing a touch.

Here's something that might make sense to a lot of you. You get a tune. You get a boost controller. Now you start turing up the boost. You can turn up the boost controller now since you have a tune? No. You just make more power than you would have without a tune.

We also have the OP here as an example. He doesn't have a tune. He has a bigger turbo. He is making more power, but knows that he can't turn up the boost real high because he will max his injectors and MAF. But he is running fine with more power.

BTW. I'm not a real big fan of the SAFC or any piggyback. I do like it's cool screen and datalogging. But I prefer an ECU tune. I tune mine quite often searching for that edge. I started tuning when my MAF went bad, and I replaced it with a Z32. That required me to modify the ECU with the new VQ map.

Gene

[RustspecS13]

rcrdps- good info about the tunning. But as for the internal WG, good luck with that. I would never mount a WG to an exhaust housing like that. I mean look at the construction, that screams I dont like heat.

Considering most are mounted to compressor housings (cold by comparison) and have longer acuating arms (connected but isolated from the hotside) so in most cases they see very little heat. But yours Id be afraid of the internals melting or being damaged and possibly either overboosting or just running open all the time.

But thats just worst case senario, since your WG is already finished, obviously try it and report back. I just dont think it'll really be all that durable.

~Alex

[rcrdps]

I didn't think it was a good idea either, but I saw where Holset shows mounts to the turbine side also.

[ReganGTS25T]

put a el cheapo fuel reg bump it up to 65 pounds lean it out with the apexi safc and the stock maf reads up to 400 crank and your good for 400 crank and stock injectors also get a wideband heh,or if your really cheap get a liquid psi gauge with a brass t put it on your fuel line get a hammer and a 1/2 inch extension and smack on the stock fuel reg till it reads something close to 65psi btw all these tips work just dont come to me if something goes wrong after what you did to the stock exhaust manifold you cant have much pride left hehe bang for the buck h1c will get you prety far its the grandfather of the modern day hx35 and all of its brothers he351w hy35 even the hx40

[rcrdps]

Sounds like my kind of thinking. No show, all go.

Gene