Gain 100HP with an intake manifold change?? - Cross post from Ferrari Chat
04-07-2016, 09:34 PM
#511
Nordschleife Master
Thanks for posting the info to the new people and reminding the older ones!
To add some numbers to the discussion:
When working the stock S4 manifold, we found the manifold to be very unbalanced runner to runner. Many have seen this and discussed the issue. CFM values ranged from around 260CFM@25" to 285CFM@25" for the one best case runner.
After destroying one cast to investigate the flow challenges, we modelled possible porting using clay and testing on the flow bench. After several tests, we came up with a mod plan that got the worst runners to just over 280CFM@25". With this, we left the 288CFM runner pretty much alone. So, after a few thousand spent on flow testing / modeling, we had a port design for a S4 intake to have a range of flow at 280CFM@25" across all 8 runners.
Next up was trying tot solve a problem in the throttle body casting. When "flappy" was closed, the upflow out of the throttle body was not balanced by about 30CFM@25". Like the intake, we destroyed a throttle casting working to see how it might be modded for better balance. While doing this investigation, it brought up the question of where to place the throttle and how large the diameter. As I recall, for a 500HP/500 lb.-ft. torque engine plan (i.e. "square" force/power), the thotttle plate needed to be about 1/4" inch larger, but the need looked to be a fairly big project.
As many know, I looked at the overall value to continue with the costly development and elected to stop. I still think about these engines often and really admire those who keep up their well engineered developments.
Cheers !
When working the stock S4 manifold, we found the manifold to be very unbalanced runner to runner. Many have seen this and discussed the issue. CFM values ranged from around 260CFM@25" to 285CFM@25" for the one best case runner.
After destroying one cast to investigate the flow challenges, we modelled possible porting using clay and testing on the flow bench. After several tests, we came up with a mod plan that got the worst runners to just over 280CFM@25". With this, we left the 288CFM runner pretty much alone. So, after a few thousand spent on flow testing / modeling, we had a port design for a S4 intake to have a range of flow at 280CFM@25" across all 8 runners.
Next up was trying tot solve a problem in the throttle body casting. When "flappy" was closed, the upflow out of the throttle body was not balanced by about 30CFM@25". Like the intake, we destroyed a throttle casting working to see how it might be modded for better balance. While doing this investigation, it brought up the question of where to place the throttle and how large the diameter. As I recall, for a 500HP/500 lb.-ft. torque engine plan (i.e. "square" force/power), the thotttle plate needed to be about 1/4" inch larger, but the need looked to be a fairly big project.
As many know, I looked at the overall value to continue with the costly development and elected to stop. I still think about these engines often and really admire those who keep up their well engineered developments.
Cheers !
for what they wished to accomplish.
04-08-2016, 08:22 AM
#513
well, the revs at the top is where the HP is, and the s4 manifold ends up very short. this drivability thing, is great for traffic and being either lazy or not interested i using the right gear when you want acceleration. IF YOU DO, then the intake has to go and no one really cares about the flappy's purpose unless you are driving around town and dont care about maximizing hp and acceleration.
I had a centrifugal supercharged 85 with an auto that put 370 hp to the wheels. It really didn't come alive until 3500 rpm but after that it was insane; low rpm was really lazy due to the 85-86 cams and the SC drag. It was fun to drive when you were hammering it but it missed having that instant power when cruising at lower rpm, and with the auto it was very easy to get caught at lower rpms and out of the sweet spot.
The market for a 928 intake that maximizes hp at the top end and sacrifices low end is is minuscule, hence why it is yet to be developed.
04-08-2016, 12:41 PM
#515
Rennlist Member
And around and around we go. Everything is a tradeoff. An intake can't just create hp out of thin air, it just takes it from one rpm and puts it higher or lower. Devices like the flappy try to give the best of both worlds. That's why modern cars have all these electronic gizmos, like VVT, variable intakes, variable vane turbos etc. All designed to make changes on the fly to give the best of both worlds. As for the comment saying only lazy street drivers need low/mid range power, if that was the case modern car manufacturers wouldn't spend millions developing all the stuff I mentioned above.
I had a centrifugal supercharged 85 with an auto that put 370 hp to the wheels. It really didn't come alive until 3500 rpm but after that it was insane; low rpm was really lazy due to the 85-86 cams and the SC drag. It was fun to drive when you were hammering it but it missed having that instant power when cruising at lower rpm, and with the auto it was very easy to get caught at lower rpms and out of the sweet spot.
The market for a 928 intake that maximizes hp at the top end and sacrifices low end is is minuscule, hence why it is yet to be developed.
I had a centrifugal supercharged 85 with an auto that put 370 hp to the wheels. It really didn't come alive until 3500 rpm but after that it was insane; low rpm was really lazy due to the 85-86 cams and the SC drag. It was fun to drive when you were hammering it but it missed having that instant power when cruising at lower rpm, and with the auto it was very easy to get caught at lower rpms and out of the sweet spot.
The market for a 928 intake that maximizes hp at the top end and sacrifices low end is is minuscule, hence why it is yet to be developed.
i think anyone that finally understands where the 928 engine or most engines in general, make their power, will agree that this well rounded intake is the small market, not the other way around. want proof??? why are all modern HIGH HP engines producing power in the form as i suggest? Most ly ALL of them!!
go look at the mustang, aston martin vantage, Ferrari, porsche ...... all are making HUGE hp now that follow the curve that ive advocated. not much grunt down low and all of the HP near the top RPM revs AND those revs are getting to the 8000rpm range and beyond by not ony the mustang V8 but all the other marquee manufacturers.... SO, dont tell me there is no market for a pure race power plate characteristics, when almost all the top exotic cars are doing this today! Sure, its nice to drive the wide HP curve (and thats what the goal of GB and the discussion here is) engine. so, maybe i shouldnt call it lazy driving, but more carefree... is that better? like a corvette engine today. big displacement.... wide HP curve . put an automatic on it and its power on demand.... good stuff.... but, dont discount pure power designs as well that only care about peak power. they are still very popular!
04-08-2016, 01:22 PM
#516
Nordschleife Master
Just a couple of comments, really no new information here:
- S3 and GT lobes measure to be the same, and different from the S4 and GTS lobes. (The factory WSM etc. data on GTS cams is way off so those should be ignored. The GTS lobes are in between S4 lobes and GT/S3 lobes in terms of size.)
- Jim Morton makes on an interesting and informative point (that he has made in the past) about the throttle body element flowing in an imbalanced way per side.
At low flow rates, that is at low rpms if you've hold the engine otherwise constant, I would think that the imbalance in the flow rates isn't a very significant issue. Of course, you'd rather have it balanced, but the air speeds in the throttle body are relatively low at low rpms.
The situation changes at high rpms when the flow rates are high, and now the imbalance can really cause some problems. Short of attempting to port the throttle body element to be balanced, wouldn't this be an argument for reconfiguring the computer to keep the flappy open at the high rpms? Or is there some reason why the Helmholtz resonator mode (flappy closed) gives some benefits? I can't see any difference in a dyno graph at high rpms with flappy closed and flappy open modes. My car just leaves the flappy open for the duration of the rpm range after it opens, and the second closing trigger point is set above the redline.
- The throttle plate diameter can be increased somewhat. I think Sterling McGee had maxbore.com modify his throttle body from the stock 74mm (or 75mm, don't recall exactly) to 79mm, which is about +14% change in area and about -12% change in velocity. I think that the throttle body in question may currently be installed in one of Roger Tyson's cars, but I'm not sure. The point being that adding a little bit of capacity to the throttle body is not terribly expensive, but going beyond 14% increase becomes a big project.
- I think that the S4 intake manifold is a good compromise that works with both manual and automatic cars. I think that if they had built a different intake manifold per transmission type, then they might have prioritized things differently for the manual car.
No new information here, just hashing up old information.
- S3 and GT lobes measure to be the same, and different from the S4 and GTS lobes. (The factory WSM etc. data on GTS cams is way off so those should be ignored. The GTS lobes are in between S4 lobes and GT/S3 lobes in terms of size.)
- Jim Morton makes on an interesting and informative point (that he has made in the past) about the throttle body element flowing in an imbalanced way per side.
At low flow rates, that is at low rpms if you've hold the engine otherwise constant, I would think that the imbalance in the flow rates isn't a very significant issue. Of course, you'd rather have it balanced, but the air speeds in the throttle body are relatively low at low rpms.
The situation changes at high rpms when the flow rates are high, and now the imbalance can really cause some problems. Short of attempting to port the throttle body element to be balanced, wouldn't this be an argument for reconfiguring the computer to keep the flappy open at the high rpms? Or is there some reason why the Helmholtz resonator mode (flappy closed) gives some benefits? I can't see any difference in a dyno graph at high rpms with flappy closed and flappy open modes. My car just leaves the flappy open for the duration of the rpm range after it opens, and the second closing trigger point is set above the redline.
- The throttle plate diameter can be increased somewhat. I think Sterling McGee had maxbore.com modify his throttle body from the stock 74mm (or 75mm, don't recall exactly) to 79mm, which is about +14% change in area and about -12% change in velocity. I think that the throttle body in question may currently be installed in one of Roger Tyson's cars, but I'm not sure. The point being that adding a little bit of capacity to the throttle body is not terribly expensive, but going beyond 14% increase becomes a big project.
- I think that the S4 intake manifold is a good compromise that works with both manual and automatic cars. I think that if they had built a different intake manifold per transmission type, then they might have prioritized things differently for the manual car.
No new information here, just hashing up old information.
Last edited by ptuomov; 04-08-2016 at 02:08 PM.
04-08-2016, 01:47 PM
#517
Rennlist Member
Just a couple of comments, really no new information here:
- S3 and GT lobes measure to be the same, and different from the S4 and GTS lobes. (The factory WSM etc. data on GTS cams is way off so those should be ignored. The GTS lobes are in between S4 lobes and GT/S3 lobes in terms of size.)
- Jim Morton makes on an interesting and informative point (that he has made in the past) about the throttle body element flowing in an imbalanced way per side.
At low flow rates, that is at low rpms if you've hold the engine otherwise constant, I would think that the imbalance in the flow rates isn't a very significant issue. Of course, you'd rather have it balanced, but the air speeds in the throttle body are relatively low at low rpms.
The situation changes at high rpms when the flow rates are high, and now the imbalance can really cause some problems. Short of attempting to port the throttle body element to be balanced, wouldn't this be an argument for reconfiguring the computer to keep the flappy open at the high rpms? Or is there some reason why the Helmholtz resonator mode (flappy closed) gives some benefits? I can't see any difference in a dyno graph at high rpms with flappy closed and flappy open modes. My car just leaves the flappy open for the duration of the rpm range after it opens, and the second closing trigger point is set above the redline.
- The throttle plate diameter can be increased somewhat. I think Sterling McGee had maxbore.com modify his throttle body from 74mm to 79mm, which is about +14% change in area and about -12% change in velocity. I think that the throttle body in question may currently be installed in one of Roger Tyson's cars, but I'm not sure. The point being that adding a little bit of capacity to the throttle body is not terribly expensive, but going beyond 14% increase becomes a big project.
- I think that the S4 intake manifold is a good compromise that works with both manual and automatic cars. I think that if they had built a different intake manifold per transmission type, then they might have prioritized things differently for the manual car.
No new information here, just hashing up old information.
- S3 and GT lobes measure to be the same, and different from the S4 and GTS lobes. (The factory WSM etc. data on GTS cams is way off so those should be ignored. The GTS lobes are in between S4 lobes and GT/S3 lobes in terms of size.)
- Jim Morton makes on an interesting and informative point (that he has made in the past) about the throttle body element flowing in an imbalanced way per side.
At low flow rates, that is at low rpms if you've hold the engine otherwise constant, I would think that the imbalance in the flow rates isn't a very significant issue. Of course, you'd rather have it balanced, but the air speeds in the throttle body are relatively low at low rpms.
The situation changes at high rpms when the flow rates are high, and now the imbalance can really cause some problems. Short of attempting to port the throttle body element to be balanced, wouldn't this be an argument for reconfiguring the computer to keep the flappy open at the high rpms? Or is there some reason why the Helmholtz resonator mode (flappy closed) gives some benefits? I can't see any difference in a dyno graph at high rpms with flappy closed and flappy open modes. My car just leaves the flappy open for the duration of the rpm range after it opens, and the second closing trigger point is set above the redline.
- The throttle plate diameter can be increased somewhat. I think Sterling McGee had maxbore.com modify his throttle body from 74mm to 79mm, which is about +14% change in area and about -12% change in velocity. I think that the throttle body in question may currently be installed in one of Roger Tyson's cars, but I'm not sure. The point being that adding a little bit of capacity to the throttle body is not terribly expensive, but going beyond 14% increase becomes a big project.
- I think that the S4 intake manifold is a good compromise that works with both manual and automatic cars. I think that if they had built a different intake manifold per transmission type, then they might have prioritized things differently for the manual car.
No new information here, just hashing up old information.
as far as the TB... you are saying the S4 TB is 74mm (2.9")?? are you kidding?
the euro 2 valve TBs are 84mm. arent the 85 US S3 TBs as large as well. (3.3" )? if so, the smalll TB couple with the unbalanced flow could be a huge difference in High RPM hp.
04-08-2016, 01:47 PM
#518
Top end is important mark, no one is saying HP is not important either. But in our market our cars are mostly driven in the street no "***** to the wall" racing like you do. Finding enough people to throw money on a top end racing I take that you advocate is going to be a tad hard in his group. Where as a more balanced intake system (like GB is making) has a better market. That's why I said maybe starting a "top end super high HP Aston/mustang look what they are doing" might be a better choice.
I just know , and you can read it here, people are tired of hashing out the same old info.
For me, here in LA, super high rpm power is neat but would not be used much except to attract "street racers" and the cops. So my ITB design is for more mid/high power just above shift points. I am not tracking it.
I just know , and you can read it here, people are tired of hashing out the same old info.
For me, here in LA, super high rpm power is neat but would not be used much except to attract "street racers" and the cops. So my ITB design is for more mid/high power just above shift points. I am not tracking it.
04-08-2016, 01:57 PM
#519
want proof??? why are all modern HIGH HP engines producing power in the form as i suggest? Most ly ALL of them!!
go look at the mustang, aston martin vantage, Ferrari, porsche ...... all are making HUGE hp now that follow the curve that ive advocated. not much grunt down low and all of the HP near the top RPM revs AND those revs are getting to the 8000rpm range and beyond by not ony the mustang V8 but all the other marquee manufacturers.... SO, dont tell me there is no market for a pure race power plate characteristics, when almost all the top exotic cars are doing this today!
go look at the mustang, aston martin vantage, Ferrari, porsche ...... all are making HUGE hp now that follow the curve that ive advocated. not much grunt down low and all of the HP near the top RPM revs AND those revs are getting to the 8000rpm range and beyond by not ony the mustang V8 but all the other marquee manufacturers.... SO, dont tell me there is no market for a pure race power plate characteristics, when almost all the top exotic cars are doing this today!
04-08-2016, 02:08 PM
#520
Nordschleife Master
I think the throttle body element has a bore at the front end that starts at 80mm. It then tapers down to the throttle plate. I think the throttle plate is either 74 or 75mm, I don't recall exactly. And I don't think the plate is exactly round, but I'm not sure.
04-08-2016, 02:08 PM
#521
Originally Posted by Cosmo Kramer
This is done using modern technology that can't be fitted to a 928 with any sort of economic reason.
04-08-2016, 02:18 PM
#522
Nordschleife Master
This raises an interesting question. Suppose that one could "port" the throttle body T-element such that the both legs of the secondary pipe would flow the same amount into the separate plenums. Would one then make more high-rpm power flappy closed? The intake manifold "makes" a little more high rpm power with the flappy closed in a 1D model because of the resonance effects, but it doesn't actually make more high rpm power in reality on a dyno. This may be because of the flow imbalance. I'm thinking that if one could cure the flow imbalance somehow, maybe then one would actually be better of utilizing the resonance effect and keeping the flappy closed at high rpms.
04-08-2016, 02:31 PM
#523
Rennlist Member
This raises an interesting question. Suppose that one could "port" the throttle body T-element such that the both legs of the secondary pipe would flow the same amount into the separate plenums. Would one then make more high-rpm power flappy closed? The intake manifold "makes" a little more high rpm power with the flappy closed in a 1D model because of the resonance effects, but it doesn't actually make more high rpm power in reality on a dyno. This may be because of the flow imbalance. I'm thinking that if one could cure the flow imbalance somehow, maybe then one would actually be better of utilizing the resonance effect and keeping the flappy closed at high rpms.
however, what you mention might be an interesting modification. i think the manifold just needs to be much larger with less restriction on the inlets. i thought that those spacers would have worked better, but that must not be the issue. i think its truly in the integrated runner set up , and TB that causes the restriction
Top end is important mark, no one is saying HP is not important either. But in our market our cars are mostly driven in the street no "***** to the wall" racing like you do. Finding enough people to throw money on a top end racing I take that you advocate is going to be a tad hard in his group. Where as a more balanced intake system (like GB is making) has a better market. That's why I said maybe starting a "top end super high HP Aston/mustang look what they are doing" might be a better choice.
I just know , and you can read it here, people are tired of hashing out the same old info.
For me, here in LA, super high rpm power is neat but would not be used much except to attract "street racers" and the cops. So my ITB design is for more mid/high power just above shift points. I am not tracking it.
I just know , and you can read it here, people are tired of hashing out the same old info.
For me, here in LA, super high rpm power is neat but would not be used much except to attract "street racers" and the cops. So my ITB design is for more mid/high power just above shift points. I am not tracking it.
04-08-2016, 02:41 PM
#524
Former Sponsor
And around and around we go. Everything is a tradeoff. An intake can't just create hp out of thin air, it just takes it from one rpm and puts it higher or lower. Devices like the flappy try to give the best of both worlds. That's why modern cars have all these electronic gizmos, like VVT, variable intakes, variable vane turbos etc. All designed to make changes on the fly to give the best of both worlds. As for the comment saying only lazy street drivers need low/mid range power, if that was the case modern car manufacturers wouldn't spend millions developing all the stuff I mentioned above.
I had a centrifugal supercharged 85 with an auto that put 370 hp to the wheels. It really didn't come alive until 3500 rpm but after that it was insane; low rpm was really lazy due to the 85-86 cams and the SC drag. It was fun to drive when you were hammering it but it missed having that instant power when cruising at lower rpm, and with the auto it was very easy to get caught at lower rpms and out of the sweet spot.
The market for a 928 intake that maximizes hp at the top end and sacrifices low end is is minuscule, hence why it is yet to be developed.
I had a centrifugal supercharged 85 with an auto that put 370 hp to the wheels. It really didn't come alive until 3500 rpm but after that it was insane; low rpm was really lazy due to the 85-86 cams and the SC drag. It was fun to drive when you were hammering it but it missed having that instant power when cruising at lower rpm, and with the auto it was very easy to get caught at lower rpms and out of the sweet spot.
The market for a 928 intake that maximizes hp at the top end and sacrifices low end is is minuscule, hence why it is yet to be developed.
Overly large runners, plenum, and butterfly for a 5.0, yet an almost a straight linear torque line from lower rpms to higher rpms. This linear torque made this car impressive to drive, through the rpm range....no "dip" from flappy....nothing but linear increases in "grunt" as the rpms increased, which continued into the higher rpm range.
Design changes in the next version will certainly increase the velocity and thus the low speed cylinder filling efficiency...tough to image the torque doing anything but increasing.
04-08-2016, 02:44 PM
#525
Rennlist Member
flat torque curve means rising HP curve. meaning, the usable HP is at the UPPER RPM range. a broad HP curve, what the flappy helps us do, is what you are looking for. most the new high end exotics, have stuff to optimize the lower end torque and HP, but its no where near as good as what we have with the 928. they do this to use a smaller lighter engine, 4.3 liter for the Aston Martin and 5 liter for the mustange and the make insane hp for their displacement, but in now way, is the HP usable in the mid or lower RPM ranges
Ive driven them both on the track.. its obvious.
i do think the AM V8 vantage intake could have the runners at the bottom lapped off and new runners with wider spacing adapted to our cars, but thats a wish. using the mustang intake is not feasible , as its composite. the the aluminum vantage intake, might be adaptable.
below: the Carrera GT HP curve just to show modern HP curve shapes
the rob edward GTS with intake power curve
the 928S4 with and without flappy closed
last the Vantage V8 4.3 liter power curve
compare the 928 to the vantage... which one has the broader HP curve!
Last edited by mark kibort; 04-08-2016 at 03:14 PM.