Looking for info on ITB plenum design
10-05-2013, 12:48 AM
#61
Rennlist Member
That sounds a sensible approach, I'm trying to keep my car on the road..
10-05-2013, 03:56 AM
#62
I have a reasonably "big" cam on the way and am not too worried about shifting the curves further up since I recently noticed that advancing cam timing can have a dramatic effect and widen the curves. It also makes sense to me that the less restricted the engine, the higher the effects of variations in cam timing.
Good point from Rod... We all take for granted that your engine Patrick sounds like it's fully derestricted on the turbine side, but checking backpressure is pretty straightforward. I'm quite sure you already have very little backpressure, but it's still a good variable to know.
And yes I confirm that the Lindsey intake is a good piece of kit, even if the plenum might be a bit small (and even if it's fugly IMO). It returned great static results on our flowbench, and on a friend's 3.0 8V using a small turbo making 2bar of backpressure it still unleashed 60hp (380 -> 440hp) at 1.2bar of boost over the stock intake, with the same 9R cam. We have another 3.0 8V in development that will be using the LR intake again, this time with a larger turbo. Unless I get off my a$$ and try to make copies of my intake.
Good point from Rod... We all take for granted that your engine Patrick sounds like it's fully derestricted on the turbine side, but checking backpressure is pretty straightforward. I'm quite sure you already have very little backpressure, but it's still a good variable to know.
And yes I confirm that the Lindsey intake is a good piece of kit, even if the plenum might be a bit small (and even if it's fugly IMO). It returned great static results on our flowbench, and on a friend's 3.0 8V using a small turbo making 2bar of backpressure it still unleashed 60hp (380 -> 440hp) at 1.2bar of boost over the stock intake, with the same 9R cam. We have another 3.0 8V in development that will be using the LR intake again, this time with a larger turbo. Unless I get off my a$$ and try to make copies of my intake.
10-05-2013, 07:24 AM
#63
"The 100-110 m/s is the AVERAGE velocity. In other words, for our 2.5L engines, you have 180 degrees of crank revolution to fill 0.625L. At 7000 RPM, that is about 0.0042 seconds. So at 110m/s, that means you need a 41mm port diameter to flow that kind of velocity. Figure your valves are 45mm, allow about 3.5mm for seat geometry, that puts you at 41.5. Allow 10% taper, maybe that takes away another 2mm or so diameter, that leaves you at 39.5mm. That puts your velocity at nearly 120m/s. So go recalculate. Honestly, I'd target 100 or so without some serious, serious work. Anyway, in those conditions, peak power at 6,000 RPM gives you 102 m/s.
10-05-2013, 09:51 AM
#64
Burning Brakes
Agreed, thanks Harry....thanks for making me dizzy. 
I would like to employ some methodology that falls somewhere inbetween NASA / MIT and what we term down here as 'Bush Mechanics'. Bush is Ozzie slang for out beyond the urban line, even beyond normal Country. This is where your wits can save your life but don't expect these mechanical examples to make it into Racecar Engineering. Conversely, without the aid of high powered computers and the people that know how to run them, or the ability to make endless intakes and compare them on the engine dyno, then we have to make a compromise. I see what Thom and others are saying too. Hopefully there is a level of intellect that can start at a point that is far from scratch. I have discussed intakes with Thom a bit recently and he has at least tried a few different ones on his 3L 8v motor plus done his own research. So I'm also prone to listening to someone like that who has more data than myself. I'm still intrigued by the LR version that seems to invoke polarity from the pack. Some have basically ridiculed it but Thom has found that it was a positive improvement on a friend's car I believe. A question that has been vexing me and sorry to keep throwing it back to my motor, but I think it's also in context of the greater discussion. Perhaps if I start it like this;
I have a friend who has a pretty highly developed 3.1 8v motor. It has a big cam and a worked head running at close to 250cfm on the flow bench with stock size ex valves and 49mm intake. It has a 700hp turbo with a smaller hotside to help with spool. It also has 4-1 headers which are larger than the SFR equivalent. Larger cooling core system and larger 66mm t/body. The components are all geared for about 7500rpm running on race grade E85 with static c/r of 8:0.1...however despite adding ign at the top end, the tuner's down here found that the motor just wants to nose off at 6k. Most fingers are pointing at the stock intake as the culprit. Sure, there could be backpressure occurring elsewhere and this friend hasn't had time/money or motivation to test it just yet as the car is proving to be pretty quick as is.
So....long story long...if this friend was to have a new intake made which has (simplified) shorter runners than stock, bellmouths and a larger plenum would the motor become more peaky by moving everything across say by 500rpm, or would it open the motor up to be able to run to 7500rpm therefore not only increasing the overall rpm but also dropping back into the turbo's efficiency range when shifting to the next gear, thus making the car more driveable??? Currently my friend has stated that the car is a little old school laggy. Not too bad but could be improved.
My friend is obliged by any thought put into his quandary.
I would like to employ some methodology that falls somewhere inbetween NASA / MIT and what we term down here as 'Bush Mechanics'. Bush is Ozzie slang for out beyond the urban line, even beyond normal Country. This is where your wits can save your life but don't expect these mechanical examples to make it into Racecar Engineering. Conversely, without the aid of high powered computers and the people that know how to run them, or the ability to make endless intakes and compare them on the engine dyno, then we have to make a compromise. I see what Thom and others are saying too. Hopefully there is a level of intellect that can start at a point that is far from scratch. I have discussed intakes with Thom a bit recently and he has at least tried a few different ones on his 3L 8v motor plus done his own research. So I'm also prone to listening to someone like that who has more data than myself. I'm still intrigued by the LR version that seems to invoke polarity from the pack. Some have basically ridiculed it but Thom has found that it was a positive improvement on a friend's car I believe. A question that has been vexing me and sorry to keep throwing it back to my motor, but I think it's also in context of the greater discussion. Perhaps if I start it like this;
I have a friend who has a pretty highly developed 3.1 8v motor. It has a big cam and a worked head running at close to 250cfm on the flow bench with stock size ex valves and 49mm intake. It has a 700hp turbo with a smaller hotside to help with spool. It also has 4-1 headers which are larger than the SFR equivalent. Larger cooling core system and larger 66mm t/body. The components are all geared for about 7500rpm running on race grade E85 with static c/r of 8:0.1...however despite adding ign at the top end, the tuner's down here found that the motor just wants to nose off at 6k. Most fingers are pointing at the stock intake as the culprit. Sure, there could be backpressure occurring elsewhere and this friend hasn't had time/money or motivation to test it just yet as the car is proving to be pretty quick as is.
So....long story long...if this friend was to have a new intake made which has (simplified) shorter runners than stock, bellmouths and a larger plenum would the motor become more peaky by moving everything across say by 500rpm, or would it open the motor up to be able to run to 7500rpm therefore not only increasing the overall rpm but also dropping back into the turbo's efficiency range when shifting to the next gear, thus making the car more driveable??? Currently my friend has stated that the car is a little old school laggy. Not too bad but could be improved.
My friend is obliged by any thought put into his quandary.
It also sounds like your friend may have too large a compressor for the smaller turbine. This may actually be making things worse as the smaller hotside will not have the torque to spin up the 700hp compressor increasing both lag and backpressure.
10-05-2013, 02:19 PM
#65
Race Car
Also, on the comments with teh cam timing, it is a pretty well established fact that advancing a cam increases lower end torque while sacrificing higher horsepower, and vice versa. IVC is the key, as air has momentum, and the higher the flow rate (RPM), the more momentum it has, making it easier to continue flowing after the piston passes BDC.
10-06-2013, 04:07 PM
#66
Rennlist Member
My engine with the JME cam should be good for 7k rpm but we found the same thing, it drops off at 6k rpm and even adding boost it makes no more power, in fact we tailed the boost off to 0.9 bar after 5500rpm. I think I have 2 main restrictions - the factory intake, and the smaller hotside. I hope to upgrade the intake when funds allow and I have a number 10 hotside which I am going to compare with the machined (to run a garrett stage 3 turbine). So I guess it is fair to say that there is no point upgrading cams and other parts to run 7k rpm and release the top end unless you address the other factory parts.
It also sounds like your friend may have too large a compressor for the smaller turbine. This may actually be making things worse as the smaller hotside will not have the torque to spin up the 700hp compressor increasing both lag and backpressure.
It also sounds like your friend may have too large a compressor for the smaller turbine. This may actually be making things worse as the smaller hotside will not have the torque to spin up the 700hp compressor increasing both lag and backpressure.
Inlet wheel: 88mm
Inlet intake: 62.5mm
Turbine wheel: 80mm
Turbine exhaust: 72mm
10-06-2013, 04:24 PM
#67
Three Wheelin'
Wauw.. Being away for 2 days and you all just blew up my head.. Nice info here!
So building the intake for my 16v is not going to be easy and i don't think it will look like anything that it has to look like.. Hopefully it will produce some kind of power..
So building the intake for my 16v is not going to be easy and i don't think it will look like anything that it has to look like.. Hopefully it will produce some kind of power..
10-06-2013, 04:42 PM
#68
Burning Brakes
That's interesting Nick. I'd also be interested in what you intend to do for the intake upgrade? I'll get some backpressure reads done in the future. Need to recheck the size of our X-over too but I know it's larger than stock, just might not be large enough. The turbo while quite large is performing as expected. The hotside is just one size down from what comes with the coldside in their catalogue as such.
Inlet wheel: 88mm
Inlet intake: 62.5mm
Turbine wheel: 80mm
Turbine exhaust: 72mm
Inlet wheel: 88mm
Inlet intake: 62.5mm
Turbine wheel: 80mm
Turbine exhaust: 72mm
On my side I have been holding off on progress, since my last tune I have a suspected bad HG and have not had time to get back into it as work has been busy and family life even busier. On the intake side I tend to lean with the results Thom et al have found on his intake and the LR intake in that they seem to open up the top end a little and let the 3.0 breath a little better. There is definitely something choking my car over 5500rpm and a 6k it hits a wall. I am 90% convinced the hotside housing is the number 1 cause (of the choking) and going back to the number 10 housing should ease this a little and make the tune a little safer. If I can just hold 1.1 bar to 6k rpm it will be 430 - 450 crank hp with the right intake (currently 400hp with the boost tailed off from 5500rpm to 0.9 bar). I found the specs on the SPS turbo I bought from Thom, from the company here in the UK that put them together for him (SPS) and it is nothing unusual - just a garrett T04e 60 trim (stage III turbine wheel with a machined kkk *8 housing). Interestingly it uses the same size turbine wheel that was fitted to my old VR5 turbo but the VR5 had a much larger compressor, which probably explains the laggy response I got from it. I know from John the newer ones are more responsive and are using different parts. So I will try the turbonectics *10 housing from my old VR5 and see where we get to. If that doesn't work I will look at a full Garrett and mod the crossover/ DP but seeing as I am so close to my final goal (450hp) I will see if I can get there with a bolt on turbo.
10-06-2013, 04:45 PM
#69
I struggle to see any sense in increasing the volume of piping between the head and the turbine as it's exactly like moving the turbine further away from the head.
10-06-2013, 04:49 PM
#70
Burning Brakes
10-06-2013, 05:41 PM
#71
Well, when looking at twin scroll exhaust manifolds readily available for other engines, it seems to me that the pipe size is not really chosen in function of the T3/T4 flange almost always used but in function of exhaust ports on the head, especially considering that all runners more or less merge together on the flange regardless of the number of cylinders (4 or 6).
10-06-2013, 08:32 PM
#72
Rennlist Member
At this stage I don't know. More tossing things up into the wind on a forum really. Until we measure b/pressure we won't know. I still have to think the stock intake is the major suspect but we'll look at this all sometime in the future. That the car is performing very well on a small tight track is good enough for me at the moment. We will be on a bigger more flowing track week after next and the lag may be even less noticeable. That's not to say that I'm satisfied with the nose off. I do want to find out what's 'wrong' with the setup and get it to sing a little more plus utilise the components in their efficiency range.
Thanks for posting your results Nick. Not that I'd wish it upon anyone but nice to see someone rowing in the same direction too. :-)
Thanks for posting your results Nick. Not that I'd wish it upon anyone but nice to see someone rowing in the same direction too. :-)
10-07-2013, 12:09 AM
#73
Race Car
You've hit on one of the things I really don't like about our cars, the exhaust. I'd really like to do a 4-2-1, to get some more length in there, and hopefully tune a little harder. But the surface area almost doubles, so more heat would be lost. Not sure what the inflection would be. And I also don'[t know if it could even be packaged.
10-07-2013, 12:15 AM
#74
What about the pics Front Range Fab has on their site? There is one I think.
You've hit on one of the things I really don't like about our cars, the exhaust. I'd really like to do a 4-2-1, to get some more length in there, and hopefully tune a little harder. But the surface area almost doubles, so more heat would be lost. Not sure what the inflection would be. And I also don'[t know if it could even be packaged.