Turbo and NA intake comparisons?
09-20-2011, 08:56 AM
#46
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I think you are thinking of "port tuning".
Port matching refers to matching the mating surfaces to help the air transition smoothly from one "part" to another. We can't change the basic design of the system (without serious r&d and custom fabrication) be we can make the parts fit together better than they did from the factory. These are mass produced parts, and there is enough variation in the mfg process, that there are small gains to be made by ensuring the parts that YOU have match and fit as best as possible.
Port matching refers to matching the mating surfaces to help the air transition smoothly from one "part" to another. We can't change the basic design of the system (without serious r&d and custom fabrication) be we can make the parts fit together better than they did from the factory. These are mass produced parts, and there is enough variation in the mfg process, that there are small gains to be made by ensuring the parts that YOU have match and fit as best as possible.
09-24-2011, 06:35 PM
#47
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Success! I picked up an n/a manifold this morning (thanks Kingston 944!) I measured the intake ports (40mm) and the throttle body intake (60mm) were the same as the turbo manifold. What they also have in common is the very rough texture inside, and the missalignment of the intake to throttlebody.
So its back on. I degreased the intake already, and gave it a good scrubbing with a brass wire wheel. Looks brand new now! I called it quits for the day after grinding the worst of the casting marks in the ports and the plenum. Still lots of work to do.
So its back on. I degreased the intake already, and gave it a good scrubbing with a brass wire wheel. Looks brand new now! I called it quits for the day after grinding the worst of the casting marks in the ports and the plenum. Still lots of work to do.
09-24-2011, 10:12 PM
#48
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Turbo and n/a manifold comparison. The n/a manifold is before any work was done to it.
Check out the casting marks, and the out of round opening compared to the gasket marks. This will be matched to the throttle body, after I open up the throttle body as well. This picture is also after degreasing. It was black and gunky.
Check out the casting marks, and the out of round opening compared to the gasket marks. This will be matched to the throttle body, after I open up the throttle body as well. This picture is also after degreasing. It was black and gunky.
10-14-2011, 08:16 AM
#49
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Small update.
I pulled off the n/a throttle body from my car so I could mark all the mating surfaces so I could match them properly. Because the parts don't line up exactly, (bolted them up, and opened the throttle plate and looked in) I marked from a fraction of a mm to almost 2mm's worth of misalignment. After some quick math, I figured that the openings were mismatched/misaligned by 2-3% Not a huge amount, but it is still blocking 2-3% of available airflow at the throttle body alone. The afm/air filter box is misaligned about the same, AND so was the paper gasket between the two, so I trimmed that as well to get it all matched up.
I already estimated 2-5% mismatch/misalingment at the intake to cyl head mating surfaces.
Where this is going, is smoothing out the intake system (replacing the rubber elbow would be my next project, as it is VERY rough due to the ribbing) could gain you anywhere from 1-5% increase in airflow. Minimal yes, but I'm sure it will help with off idle throttle response, and WOT. Best part is the cost to me. $0.00
Edit.
Also of note is that I measured the runner lengths on both manifolds, and all the runners on the turbo intake are the same length, and so are the runners of the n/a manifold. I didn't record the actual length of the runners. (I used a rubber hose inserted into the runner and then compared the length from runner to runner give or take a couple of mm's.)
I pulled off the n/a throttle body from my car so I could mark all the mating surfaces so I could match them properly. Because the parts don't line up exactly, (bolted them up, and opened the throttle plate and looked in) I marked from a fraction of a mm to almost 2mm's worth of misalignment. After some quick math, I figured that the openings were mismatched/misaligned by 2-3% Not a huge amount, but it is still blocking 2-3% of available airflow at the throttle body alone. The afm/air filter box is misaligned about the same, AND so was the paper gasket between the two, so I trimmed that as well to get it all matched up.
I already estimated 2-5% mismatch/misalingment at the intake to cyl head mating surfaces.
Where this is going, is smoothing out the intake system (replacing the rubber elbow would be my next project, as it is VERY rough due to the ribbing) could gain you anywhere from 1-5% increase in airflow. Minimal yes, but I'm sure it will help with off idle throttle response, and WOT. Best part is the cost to me. $0.00
Edit.
Also of note is that I measured the runner lengths on both manifolds, and all the runners on the turbo intake are the same length, and so are the runners of the n/a manifold. I didn't record the actual length of the runners. (I used a rubber hose inserted into the runner and then compared the length from runner to runner give or take a couple of mm's.)
Last edited by ZR8ED; 10-14-2011 at 01:10 PM. Reason: information added
10-14-2011, 10:46 PM
#51
Been there done this.
Going from memory since the data is at home. The turbo runners are almost the same diameter and length as the NA. The NA plenum is bigger which helps feed the motor at higher RPM's. Swapping them made very little performance difference, as measured on a Dynojet.
Plenum size, runner diameter, and runner length all control the peak HP and Tq points, but do not necessarily raise the peaks.
I made a custom short runner, large plenum NA intake and it moved the Hp and Tq peaks up about 4-500RPM's which was desirable. It was not huge but every little bit counts when raicng. If this is for a street/track application it is not worth the effort. That was with a straight through "ram air" type filter set-up.
Speedforce Racing has some really nice custom intakes if you want to pick-up an off the shelf model too. the barn door is still the weak link so if you can MAF around that it may increase the performance.
Going from memory since the data is at home. The turbo runners are almost the same diameter and length as the NA. The NA plenum is bigger which helps feed the motor at higher RPM's. Swapping them made very little performance difference, as measured on a Dynojet.
Plenum size, runner diameter, and runner length all control the peak HP and Tq points, but do not necessarily raise the peaks.
I made a custom short runner, large plenum NA intake and it moved the Hp and Tq peaks up about 4-500RPM's which was desirable. It was not huge but every little bit counts when raicng. If this is for a street/track application it is not worth the effort. That was with a straight through "ram air" type filter set-up.
Speedforce Racing has some really nice custom intakes if you want to pick-up an off the shelf model too. the barn door is still the weak link so if you can MAF around that it may increase the performance.
heres a link to the thread https://rennlist.com/forums/924-931-...iscussion.html
10-14-2011, 11:11 PM
#52
any pic's of the custom intake you had? i am throwing around the idea for my 8v i think with the 10.2/1 comp it might help out a good bit
heres a link to the thread https://rennlist.com/forums/924-931-...iscussion.html
heres a link to the thread https://rennlist.com/forums/924-931-...iscussion.html
I have always wondered if heat wrapping the intake will keep the air slightly cooler that bare metal or painted?
10-15-2011, 12:46 AM
#53
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In ye olde times when we had to tune accelerator pumps there might have been such a thing as "throttle response" that did not mean horsepower, it meant overcoming a serious fueling problem brought on by the inadequacy of the system to respond to a dynamic condition. Since the invention of decent EFI and the TPS or WOT switch I kinda think the concept of "throttle response" has become another form of a butt-dyno consolation prize.
But that's my opinion and I could be wrong. Anyone?
-Joel.
10-15-2011, 01:22 AM
#54
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my definition of throttle response is the time taken between blipping/flooring/modifying the throttle pedal and the change in revs of the engine...so like...can you just flip the motor around the rpm range by bouncing your foot on the pedal
10-15-2011, 09:02 AM
#55
when i read this all i could think was yesterday i ran both my 83 944 parts car and my 88 924s and cant get over how different they are the 44 feels like it takes for even to rev up but the 24 jumps up there in a moments notice
10-15-2011, 03:48 PM
#57
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You know I have heard of this "throttle response" and honestly I have no idea what it means. If I step on the throttle I expect the engine to produce more HP and respond. What is it going to respond with if it's not going to start making more power? Enthusiastic noises?
In ye olde times when we had to tune accelerator pumps there might have been such a thing as "throttle response" that did not mean horsepower, it meant overcoming a serious fueling problem brought on by the inadequacy of the system to respond to a dynamic condition. Since the invention of decent EFI and the TPS or WOT switch I kinda think the concept of "throttle response" has become another form of a butt-dyno consolation prize.
But that's my opinion and I could be wrong. Anyone?
-Joel.
In ye olde times when we had to tune accelerator pumps there might have been such a thing as "throttle response" that did not mean horsepower, it meant overcoming a serious fueling problem brought on by the inadequacy of the system to respond to a dynamic condition. Since the invention of decent EFI and the TPS or WOT switch I kinda think the concept of "throttle response" has become another form of a butt-dyno consolation prize.
But that's my opinion and I could be wrong. Anyone?
-Joel.
I'm going to measure the intake volumes this weekend for myself and will report back.
10-16-2011, 11:31 AM
#58
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Hmm, I'm skeptical. It sounds like you want to improve throttle response by decreasing the amount of time between the throttle plate opening and more air being fueled, compressed and ignited. I think to do this in some meaningful way you need to go to ITBs or a 4-vale head with variable manifold runner geometry.
I believe the airflow through the engine is around 10 m/s so if you reduced the path an air molecule had to take by 1m you could have 1/10 of a second less lag, except in reality you have airbox volume and manifold Helmholtz resonance factors and stuff like that which would I believe reduce the amount of gain that'd be on the table. Plus 1m is a long ways in a manifold and you'd be working with 1/10 that number.
Swapping one traditional manifold for another is not IMO going to reduce the lag enough to actually feel or measure given that you cannot make a really big change in the distance and volume.
A case where you might perceive better 'throttle response' could be from moving the power band, which might be the practical effect you are going for. In that case IMO you would not really be reducing throttle lag but rather putting a bump in your powerband in a place where you want it, probably at the expense of another part of the power band.
-Joel
I believe the airflow through the engine is around 10 m/s so if you reduced the path an air molecule had to take by 1m you could have 1/10 of a second less lag, except in reality you have airbox volume and manifold Helmholtz resonance factors and stuff like that which would I believe reduce the amount of gain that'd be on the table. Plus 1m is a long ways in a manifold and you'd be working with 1/10 that number.
Swapping one traditional manifold for another is not IMO going to reduce the lag enough to actually feel or measure given that you cannot make a really big change in the distance and volume.
A case where you might perceive better 'throttle response' could be from moving the power band, which might be the practical effect you are going for. In that case IMO you would not really be reducing throttle lag but rather putting a bump in your powerband in a place where you want it, probably at the expense of another part of the power band.
-Joel
10-16-2011, 05:13 PM
#59
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Measured the volume of the two intakes today.
I blocked off all the ports/openings, and filled the entire manifold with water.
The n/a manifold held approximately 3l of water. The turbo manifold held 3.25l of water. I was unable to accurately measure the main plenum itself. I could not see well enough inside to tell when it was full so the only way to measure was fill the entire manifold.
Interesting to see these results. Based on others information, it must be that the main plenum itself is larger.
I blocked off all the ports/openings, and filled the entire manifold with water.
The n/a manifold held approximately 3l of water. The turbo manifold held 3.25l of water. I was unable to accurately measure the main plenum itself. I could not see well enough inside to tell when it was full so the only way to measure was fill the entire manifold.
Interesting to see these results. Based on others information, it must be that the main plenum itself is larger.