Thanks for the suggestion, actually you were BOTH right believe it or not

I have been busting my *** over time the past week on this project, last night I swapped the turbine housing and tonight after tuning a Rally Evo X I got down to business on the dyno to test my Evo with the larger .81 T4 a.r back housing

Suprize / Suprize - zero effect on spool up or boost - none




The power picked back up with the Headway head with the larger back housing back to near where I was on the stock head with the smaller housing

Frankly, I was totally shocked to see that the spool up is nearly identical and the car easily makes loads of boost



Still - we are not seeing any gains with the Headway head which is very suprizing

Next up I looked at the plugs which looked fine



Then - per Dave's suggestion a compression test which identified one low cylinder and a leak down test which showed 40 % leak down in one clyinder

Now its time to take the head back off and try and figure out where the leak comes from

Thanks to Ramone and Dave for all the advice and suggestions

Given that the car ran fine with the .81 a/r turbine housing and the spool up is identical, I am going to get the next bigger size a/r housing on there while I am at the engine repair

Back to the drawing board

Sometimes, finding the right combination can take a lot of effort and trial and error.

Al

 

Sounds like progress!

Was the leaking air going through valves or rings?

 

I agree with that idea. The changes it makes will not necessarily be manifested as differences in spool on the dyno, so don't put too much emphasis on that. .81 A/R TS T4 is small for anything in that power range.

Regarding the turbine wheel and turbine housing, are you absolutely certain that the turbine housing is competently machined for that particular wheel? Does the maker of the wheel also provide the housing? I know that is an unusual question, but . . .

 

Interesting find on the leakage. That could be part of it, but I would not be surprised if it was like that during the pull with the stock head. If you told me that a few years ago, I would of said you are nuts. However after working on alcohol funny cars that get leaked down every round, I would believe it. I have seen cars go down the track with 50 and 60% leakage, in a cylinder and there was not a noticeable difference. I would also think that the lack of difference in spool, especially going with the larger a/r, would point to the leakage being there for all tests. Hopefully the leakage is in the top half so the shortblock does not have to be taken apart. Before I tore anything apart in the short block I would vacum test the ports on the head.

 

Head work on the 4g63 is for those who need curbside appeal when they build their engine. Finding HP is more about a finding a combination of parts that work well together. You DONT need to change flow of head. You just re-proved that with your headgames head test.

There are 6 things off the top of my head that dictate flow for HP. compression, cams, intake manifold, ex manifold, A/R of housing. head port size. There is no ultimate best for any one of those. trying to find "best head flow" is only gonna be good for the current combo of parts you are testing them with. changing only one parameter is only good for that current combo of parts.

This fact was learned about 6 years ago in the DSM community. All the 4g63 head needs is good valve job and 15 minute bowl cleanup. Spending anything beyond that on the head is a waste of money. Changing the rest of the parts to get the HP you want is far easier and far cheaper.

one year at the shootout there were two top racers (one was magnus, other dont know) that damaged their high HP heads and had to bolt on bone stock heads in order to finish competing. one team set new ET record for his car at the time. the other went faster MPH than he previously had. then there were threads that started on the subject. and dozens admitted spending thousands on head work and not seeing any gain, many reported actual losses.

 

It was a Headway head NOT HeadGames.

 

His testing is not to find out which head flows more. It is too figure out what makes more hp. And he is not changing just one parameter. He has tested at high and low boost levels, changed housings and is entertaining the thought of putting his 42r back on. Other than that, you share similar opinions to myself, but 15 mins of bowl clean up is a little underestimated, and there are a couple more areas to look at other than the bowl. Especially if os valves are used. Not saying they are needed mind you.. There has been a lot of talk about port size. Reality is on these heads there is not much you can do in the intake runners to make them much larger. In the exhaust, since we are talking about turbo cars here, if you can't make the cross sectional area behind the valves much larger, then opening up the runner is only going to reduce velocity, and imo slow spool. Again this is why he is testing.. To find the truth. Al may not find the perfect combo by any means for any 4g63, however I think he will definitely shed some light on the subject, and open some minds/change perspective.

 

but I have the cutest thong!! all it takes is a couple 's and I look good



Then - per Dave's suggestion a compression test which identified one low cylinder and a leak down test which showed 40 % leak down in one clyinder

Now its time to take the head back off and try and figure out where the leak comes from

Thanks to Ramone and Dave for all the advice and suggestions

Al[/QUOTE]

Your very welcome...but when you do a leak down, that is when you listen to where it's leaking into. It can only be the valve or the rings..and it's alot less work then looking at everything apart, guessing and or taking things apart that wouldn't need to be taken apart. good luck bro..you got some work ahead of ya!

 

I agree the lean was there for sure at all times, maybe just a lazy ring.

We'll soon see.

The city never sleeps!

Al

 

Jimib, I understand what he is trying to do. I clearly stated making HP is about finding a good combination of parts that work well together. As did Al, in his first post. What I was trying to convey is for 99.9% of people reading spending money on cylinder head is not wise. Al was making a solid 808whp on the bone stock head, he bolts in a 3500+ cylinder head and the combination looses 35hp. This is exactly what happened at the shootout when two racers went faster with bone stock heads. Al was not around for the early DSM shootout days. This was before his time with the 4g63.

You can take a bone stock engine and port the head and get 25whp. Or you can take the same bone stock engine and bolt in cams and get 25whp. Which is easier and which is smarter?

making a head flow better is easy. making a combination of parts around that better flowing head is not so easy. bolting heads in and out to see what works and what doesnt is about as time consuming as it gets.

I admire anyone like Al, that takes the time to do back to back testing and shares it with the boards. I would have been excited to see you dont need to spend 3500 on a cylinder head to make a potent 800whp. What this means is if you dont need it for 800 then you dont need it for 600 and you dont need it for 400. This is something I learned when the shootout accidentally proved it years ago. Since that time I always steer people away from spending money on cylinder head flow.

I am the type of person who does a lot of parts testing to get a combination of parts that work well together. I know what its all about. My own car has had a long list of parts installed on it to find what works and what doesnt.

Take it as you will. Not trying to start problems. Just stating what I feel is good knowledge to be gained.

Magnus head at shootout was quite an exotic head with titanium valves with smaller stems to improve flow. STOCK head proved better......

 

Your very welcome...but when you do a leak down, that is when you listen to where it's leaking into. It can only be the valve or the rings..and it's alot less work then looking at everything apart, guessing and or taking things apart that wouldn't need to be taken apart. good luck bro..you got some work ahead of ya![/QUOTE]

I agree with your ideas. I tried to identify the source of the air but it was difficult to do with the manifold in place

My plan is to take off the manifold and intake and then see if its comming out of either head port

 

If you open the oil cap and hear or even feel it then it is the rings.

If you hear noise from either manifold then it is the head.

I'm sure you know that already Al but I'm just stating my understanding to get confirmation from you smarter guys.

 

You are preaching to the choir bro lol. I said I mostly agree with you. Earlier in the thread I already mentioned rau and others had swapped stock heads on and didn't notice a difference.

 

When this type of thing occurs, there are two ways one can choose to view it:

(1) Ported heads don't increase power.

(2) Ported heads deliver increased power potential, and realizing that potential is dependent upon other factors that may not be entirely understood or may be often overlooked.


It's easy to choose #1 and make ourselves feel better by dismissing something we don't completely understand. But of course, this seems silly, as the value of airflow is as proven as the Earth is round.

Conclusion #2 tells us that the picture is more involved than it seems on the surface, and understanding that picture is the key to improving power. Bolting on parts and cranking boost pressure is easy. Understanding how airflow behaves inside an engine is far more involved than what the naked eye reveals.

Not everyone will bolt on 150whp as did AMS when switching from a Cosworth head to a CNC ported head. Understanding how to obtain that result consistently holds a great deal of value.

 

This is mad but I love the power readings. Good work.