wisconsin car club (balts and ions)
Member
Joined: 02-19-09
Posts: 220
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From: St. Louis
why only the exhaust side?
Member
Joined: 04-13-08
Posts: 240
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From: West Allis , WI
im gunna take it to extreme speed in racine, $450 for port and polish, im gunna go with .5mm oversive valves and some heavier springs
Junior Member
Joined: 08-04-08
Posts: 375
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From: Waste Allis Wisconsin
And why weren't you at the union meeting tonight???????????????
It applies but the ratio is different. Hold on. I'll search for it. 
Ok. Here is what I was looking for to help explain what I am talking about.
Before going into too much detail, there are a few things about SC'd engines that you need to know.
1) Higher exhaust flow in an SC'd will yield more power. That can be achieved in three ways; higher port flow, higher valve lift, or longer lobe duration.
2) The power delivery of the combustion cycle actually happens later than in a turbo or NA engine. Opening the exhaust valve too soon, can actually hurt performance, as a majority of the energy is being lost out the exhaust.
3) .... I won't go into that now.... it's a camshaft thing.
With that said; we know that a longer duration can potentially hurt performance. Therefore we should achieve maximum exhaust flow via higher lift and higher port flow.
It has been shown in the past (with other SC'd engines) that the ideal exhaust flow (rule of thumb) should be ~80% of the intake flow... for higher boosted engines, that can be upward of 85%. It has also been shown that to get the optimal exhaust flow ratio, it can be beneficial to sacrifice intake flow.
Of course there are various factors that come into play when finding the optimal port flow, so don't take the above numbers to heart.
Now... I know that some people call BS on the I/E ratio stuff.... however think of it like this; what goes in, must come out. Properly balancing your intake and exhaust is very critical.
Like he said in some cases it is ok to give up intake flow to get a better exhaust flow ratio.
Here is a good example of what I am talking about.
According to m2m the LSJ stock head flow 261s CFM on the intake and 149 CFM on the exhaust at .500 lift.
149/261 = 57% ratio.
m2m's CNC ported head flows 298 CFM on the intake and 206 CFM on the exhaust side at .500 lift.
206/298 = 69% ratio.
If you got the exhaust ports ported by m2m and left the intake ports alone that would give you...
206/261 = 79% ratio.
The 79% ratio is much more ideal for hp.
Ok. Here is what I was looking for to help explain what I am talking about.
Originally Posted by Someone who does not come to CSS
Before going into too much detail, there are a few things about SC'd engines that you need to know.
1) Higher exhaust flow in an SC'd will yield more power. That can be achieved in three ways; higher port flow, higher valve lift, or longer lobe duration.
2) The power delivery of the combustion cycle actually happens later than in a turbo or NA engine. Opening the exhaust valve too soon, can actually hurt performance, as a majority of the energy is being lost out the exhaust.
3) .... I won't go into that now.... it's a camshaft thing.
With that said; we know that a longer duration can potentially hurt performance. Therefore we should achieve maximum exhaust flow via higher lift and higher port flow.
It has been shown in the past (with other SC'd engines) that the ideal exhaust flow (rule of thumb) should be ~80% of the intake flow... for higher boosted engines, that can be upward of 85%. It has also been shown that to get the optimal exhaust flow ratio, it can be beneficial to sacrifice intake flow.
Of course there are various factors that come into play when finding the optimal port flow, so don't take the above numbers to heart.
Now... I know that some people call BS on the I/E ratio stuff.... however think of it like this; what goes in, must come out. Properly balancing your intake and exhaust is very critical.
Here is a good example of what I am talking about.
According to m2m the LSJ stock head flow 261s CFM on the intake and 149 CFM on the exhaust at .500 lift.
149/261 = 57% ratio.
m2m's CNC ported head flows 298 CFM on the intake and 206 CFM on the exhaust side at .500 lift.
206/298 = 69% ratio.
If you got the exhaust ports ported by m2m and left the intake ports alone that would give you...
206/261 = 79% ratio.
The 79% ratio is much more ideal for hp.
Last edited by ebristol; Apr 8, 2009 at 01:10 AM. Reason: Automerged Doublepost
Senior Member
Joined: 03-31-07
Posts: 1,294
Likes: 0
From: Milwaukee, WI
Thanks.
I bought a TVS. Bought a clutch. Bought another turbo! lol
Hopefully the TVS will be here this week. I took off all my mods in the fall to take my car to the stealership before my warrenty ran out. Everything looked good. So I have been putting all my mods back on. I will be installing that header and a dual pass endplate tonight.
I still don't know what I am going to do about that clutch. Would you even have room in your garage to do it? I have also been talking to Ryan. I might have the stealership do it and get it over with.
I picked up a slightly used Hahn S20g and Hahn turbo exhaust manifold last week. I got a steal on it and could not pass it up. Tuna is looking at it but he has sort of shifted to a TVS. If he don't want it I might sell it or keep it and turbo my car over the winter for fun. Then I might try twincharging just so I can say I tried it. IDK yet.
I might build my engine over the winter too. Diamond pistons, ARP head studs and a ported head.
Other then that not much is new. I sold my M62 and I have not been able to drive my car for almost 2 months! Its driving me nuts!!! Esp with this nice weather.
I see your single. Did the wifey finally give you the boot? lolz
I bought a TVS. Bought a clutch. Bought another turbo! lol
Hopefully the TVS will be here this week. I took off all my mods in the fall to take my car to the stealership before my warrenty ran out. Everything looked good. So I have been putting all my mods back on. I will be installing that header and a dual pass endplate tonight.
I still don't know what I am going to do about that clutch. Would you even have room in your garage to do it? I have also been talking to Ryan. I might have the stealership do it and get it over with.
I picked up a slightly used Hahn S20g and Hahn turbo exhaust manifold last week. I got a steal on it and could not pass it up. Tuna is looking at it but he has sort of shifted to a TVS. If he don't want it I might sell it or keep it and turbo my car over the winter for fun. Then I might try twincharging just so I can say I tried it. IDK yet.
I might build my engine over the winter too. Diamond pistons, ARP head studs and a ported head.
Other then that not much is new. I sold my M62 and I have not been able to drive my car for almost 2 months! Its driving me nuts!!! Esp with this nice weather.
I see your single. Did the wifey finally give you the boot? lolz
yea I just did pauls car in my garage... its a long job that i normally do way under priced cause im a nice guy but yea I have all the stuff to do it... first jordan needs to get his ass rollin and get his car back together instead of leaving it sit where I left it cause he couldnt find the wheel lock key. honestly twin charge is cool but nothing can surpass pure power of a turbo car. tvs will get most where they want but I just cant stand the heat a supercharger creates so thats why i never went that route.
no gf is around... driving me nuts
I heard what you are saying. I have heard it all before many many times. The reason I would try it is not because I think twincharging is better then going straight turbo. Its because I think it is cheaper and I don't think it is hard hard as everyone makes it sound.
Say if I used this Hahn 20g and a stock M62 as my example.
I know that at the same boost pressure say 15psi, the 20g all by itself will make more hp then a twincharge setup where the 20g is feeding the M62 at the same psi. (psi is a bad example because it does not take CFM into consideration. But lets not worry about that for now.)
But I don't think the difference is that big. Maybe 10-15whp.
And then I want to turn up the boost to say 20psi. And then compare the differences.
This is the main reason I want to try is to clear up these questions. Every talks like they know all about it but it has not been tried for a long time.
Idk. I really don't do any research on NA vehicles.
New Member
Joined: 04-05-08
Posts: 49
Likes: 0
From: Milwaukee, WI
Anyway, Derek and I will be meeting up with everyone in Kenosha on the 24th and we will have both balts and I think Jimbo is going to be with us too.
Senior Member
Joined: 11-02-07
Posts: 2,435
Likes: 0
From: Waupun, WI!
i'll be hittign up the midwest meet.
i know ryan from my town will be to, idk if he is driving or not tho.
hopefully my car wil be running good
aka new clutch
i know ryan from my town will be to, idk if he is driving or not tho.
hopefully my car wil be running good
aka new clutch
Last edited by Preston; Apr 12, 2009 at 03:30 PM. Reason: Automerged Doublepost
