I'm sure your aware of this Andrew but with good rev matching your able to stay on full boost on stock setups on both the SE and the SP.
The turbos for both cars are different. I'm lead to believe many upgrade to the gt2560r which is what the SP has. The SE runs lower compression from the factory and doesn't have VVT. The head can take more power on stock internals.
Technical(ish) Turbo Discussion
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Hjt
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Re: Technical(ish) Turbo Discussion
Hjt wrote:I'm sure your aware of this Andrew but with good rev matching your able to stay on full boost on stock setups on both the SE and the SP.
The turbos for both cars are different. I'm lead to believe many upgrade to the gt2560r which is what the SP has. The SE runs lower compression from the factory and doesn't have VVT. The head can take more power on stock internals.
Well from what I learn't, just keeping the rev's up high won't eliminate lag, but it will reduce the time it takes to fully load the engine, allowing full boost production, (so in summary yeah!
)Thanks for the input Dan Lokiel Zossy and others, got heaps from this.
Regarding the tubular vs log manifolds.
I presume a tubular allows smoother exhaust gas flow, and therefore the turbo spools up quicker.
How better would you expect for this sort of set up?
Andrew Cooper
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NitroDann
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Re: Technical(ish) Turbo Discussion
Actually theres not a lot in it would you believe.
My last log manifold, which you can read about and watch the build process started spooling at 2000rpm.
The benefits come in when you want to get the last 10 or 20 horsepower out of a slightly undersized turbo, or are pushing over 300rwhp easily.
Dann
My last log manifold, which you can read about and watch the build process started spooling at 2000rpm.
The benefits come in when you want to get the last 10 or 20 horsepower out of a slightly undersized turbo, or are pushing over 300rwhp easily.
Dann
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Orphan
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Re: Technical(ish) Turbo Discussion
Dann is correct.
While log manifolds are usually not ideal a non equal length or semi log (some of the runners merge) will generally be more responsive than an equal length manifold and not lose out on much top end power. The only real exception is true twin scroll equal length manifolds, they usually spool quite decently compared to a regular equal length manifold. The key is to get the runners to flow smoothly rather than interrupt each other which is the case with the bog standard log manifold, example below:
Something more like this is more ideal when it comes to log/merged runner collectors. The only real improvement on it would be to have runner 2 and 3 being long radius bends flowing towards the collector.
If you look at the first picture the runners allow the exhaust from runners 2 and 3 to work against the exhaust from 1 and 4 creating turbulence and slowing down flow. Gotta keep it pointing in the right direction.
The below manifold is the cast manifold from an SR20DET, the runners are actually quite small due to the thickness of the casting. PowerTune got around 270rwkw out of an engine using this and a T2 flanged turbo which are generally regarded to flow worse than their T3 equivalents. They have some dyno's backing up that that GT2871R T3 spools up faster than the smaller T2.
There is certainly no need for an equal length manifold on an MX5 unless you are shooting for some serious numbers around or in excess of 300rwkw. Also remember that most equal length manifolds can weigh significantly more than a log or unequal length manifold. Lighter + more responsive = win.
Something similar to the second manifold will easily flow enough for the high 200rwkw range, more than is really suitable in an MX5. I think the ideal choice would be that manifold with runners 2 and 3 bending towards the collector and a T25 or T28 depending on power goals. The T28 ball bearing should be good for around 180-200rwkw @ 1 bar (14.7), you can push them a little more but they are out off their efficiency much above 16psi and just serve to heat the air to ridiculous temps.
From what I have read most people seem to think that 250rwhp (188rwkw) is the the point the stock rods start to let go so the smaller T25 may be the best option on a stock bottom end as it will be maxing out just under that limit and spooling slightly quicker than the T28 though not by much and are dirt cheap not that second hand T28bb's are all that pricey, can pick one up for under $500, T25's are usually had for under $300 and rebuild kits are cheap though shops often charge a fair bit to balance them.
While log manifolds are usually not ideal a non equal length or semi log (some of the runners merge) will generally be more responsive than an equal length manifold and not lose out on much top end power. The only real exception is true twin scroll equal length manifolds, they usually spool quite decently compared to a regular equal length manifold. The key is to get the runners to flow smoothly rather than interrupt each other which is the case with the bog standard log manifold, example below:
Something more like this is more ideal when it comes to log/merged runner collectors. The only real improvement on it would be to have runner 2 and 3 being long radius bends flowing towards the collector.
If you look at the first picture the runners allow the exhaust from runners 2 and 3 to work against the exhaust from 1 and 4 creating turbulence and slowing down flow. Gotta keep it pointing in the right direction.
The below manifold is the cast manifold from an SR20DET, the runners are actually quite small due to the thickness of the casting. PowerTune got around 270rwkw out of an engine using this and a T2 flanged turbo which are generally regarded to flow worse than their T3 equivalents. They have some dyno's backing up that that GT2871R T3 spools up faster than the smaller T2.
There is certainly no need for an equal length manifold on an MX5 unless you are shooting for some serious numbers around or in excess of 300rwkw. Also remember that most equal length manifolds can weigh significantly more than a log or unequal length manifold. Lighter + more responsive = win.
Something similar to the second manifold will easily flow enough for the high 200rwkw range, more than is really suitable in an MX5. I think the ideal choice would be that manifold with runners 2 and 3 bending towards the collector and a T25 or T28 depending on power goals. The T28 ball bearing should be good for around 180-200rwkw @ 1 bar (14.7), you can push them a little more but they are out off their efficiency much above 16psi and just serve to heat the air to ridiculous temps.
From what I have read most people seem to think that 250rwhp (188rwkw) is the the point the stock rods start to let go so the smaller T25 may be the best option on a stock bottom end as it will be maxing out just under that limit and spooling slightly quicker than the T28 though not by much and are dirt cheap not that second hand T28bb's are all that pricey, can pick one up for under $500, T25's are usually had for under $300 and rebuild kits are cheap though shops often charge a fair bit to balance them.
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