Pump Gas Limitations

I bet a 4L with twin GT35's could run mid/upper 20's boost on 93. Like mentioned, most of these setups are much more efficient on the exhaust side of things than most of our cars. "big" to us is still TD05 or T3 with a small a/r.

Jason

Since we are comparing the 3s to other platforms I would simply say that the head design plays a huge part . Someone should post some stock flow numbers between different heads .

Stan Weiss' - Cylinder Head Flow Data at 28 Inches of Water -- DFW / FLW Flow Files for use with Engine Simulation Software

Check that out, a vr-4 is on there as well as mostly everything else. 242/212 @ .400 and 28 inches. Jrod's head guy claims 304 intake after their work, DR probably similar.

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Originally Posted by masterjr33

im still going with crappy manifolds causing to much exhaust gas restriction.if you cant clear the stock chambers of recently burnt fuel and gas that is 1400* plus. how are you going to effectivly control the next mitxture coming in from pre igniting.

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I was up to 930-970C all day yesterday road racing. 1700-1770F. This was at 11 psi with 9b's.

To my knowledge, the 3S heads really aren't that bad. The 300zx heads flow worse and they have two log style exhaust manifolds. Major factor would be that they have two bigger Turbos. A BPU 300zx makes 400-425 wheel at low 20-something psi. They don't hold that to redline tho. Restrictive hotside lol

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Has anyone done a dyno on Mivec heads with pump gas? I know Itallo and the guy with the Eclipse Mivec 3.8L motor have both made 800-1000AWHP plus on race gas or ethanol, but I couldn't remember what they were able to run on pump. Unported those Mivec heads flow better than our Stage III heads iirc. I know ported with bigger valves the Mivec flows better for sure. Both of those owners have bigger manifolds, exhausts, intakes, intercooler pipes, etc to make a more efficient setup. If they can't run more than 20-23 psi, then there's something else holding us back or it just isn't possible due to the inefficient design of an older V6 compared to a new 4-cylinder.

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Originally Posted by TurboSinceBirth

Has anyone done a dyno on Mivec heads with pump gas? I know Itallo and the guy with the Eclipse Mivec 3.8L motor have both made 800-1000AWHP plus on race gas or ethanol, but I couldn't remember what they were able to run on pump. Unported those Mivec heads flow better than our Stage III heads iirc. I know ported with bigger valves the Mivec flows better for sure. Both of those owners have bigger manifolds, exhausts, intakes, intercooler pipes, etc to make a more efficient setup. If they can't run more than 20-23 psi, then there's something else holding us back or it just isn't possible due to the inefficient design of an older V6 compared to a new 4-cylinder.

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thats what i was saying earlier when i posted the vid (leonels car). him and italo have the same setup except italo has slightly different turbos and mivec. bottom ends and manifolds are the same iirc. thats kinda why i lean on cams being the culprit because many people have changed every other variable but as anyonebutme always says, there are no truly *good* cams made for our cars yet. you are almost certain to not gain max potential power with just a cam swap unless you put adjustable cam gears on there too. i wish someone on here had the pull to investigate into getting cams made and swapping them in for direct comparison

After so much effort and work that has been put into developing the Flash ECU for our platform, making and testing a set of cams should definitely be doable. EVO's regularly pick up 40whp with a cam swap with supporting mods. We've also got quite a few technical savy 3/s gurus still with the platform...its just a matter of time IMO.

Back in 2002 Carroll Smith showed up at a race I was at. I ran into him and convinced him to come look at my car (the Talon) because in the space of 24 hours it had gone from a championship winner to undrivable at the same track, same weather, same tires and I was at my wit's end figuring out why.

Carroll looks at the car and starts asking me questions. I have NO answers. Lots of "I think this" and "the general consensus on the Internet is this" but nothing specific to my car.

After 20 min of bullshit and blank stares, a visibly frustrated Carroll says "dear God man, you're supposed to be the engineer here. If you don't know these answers, how the hell am I supposed to know?"

It was like being shot in the head with a diamond -and revolutionized my approach to car setup. Suspension got measured and modeled. Sensors got added and logged. Shocks and springs were measured and dynoed. You name it, I did it - and I learned a shitload about suspension tuning, including highlighting all the stuff I (and most other people) got wrong (and discovered too that most shock companies made shit and had no idea).

I very much support this topic; I'm moving to New Brunswick this summer and will lose access to Sunoco 94. I'm going to have to re-tune the car for 91 octane and I'm keen to see what people find.

But if you are gonna do it, do it right. Wanna know the difference between the EVO head and the 3G? Buy an EVO head and break out the calipers. CC the combustion chambers. Make rubber casts of the head passages and compare them. Slice up those casts and compare sectional area and shape. Break out the band saw and cut some heads open, look at wall thicknesses, look at coolant flows. Build a flow bench (or rent time on one) and get real flow numbers you can trust. Measure cam profiles. Detail every way that the heads differ, and every way that they are the same. Grab some stock intercooler pipes, compare length and volume. Etc etc etc.

I have some books from the 80s that do this with Pontiac motors (real Pontiacs, not the Chevy stuff) that details the similarities and differences between every single engine Pontiac ever made - head castings, camshafts, cranks - the works. Flow numbers, valve sizes, port shapes, chamber CC for every single head casting. All cam specs for every single OEM cam part number. And this predates digital publishing - these books were put together the old fashioned way, with scissors, typewriters, and rubber cement before going to camera and Linotype. Those old skool guys had their shit wired; they were working when it was much harder to communicate, they did it in less time, and in some cases, with smaller production numbers from which to source examples (not a whole lot of RamAir IV parts to measure, and they even had details on the prototyped - but never released publicly - Ram Air V)

Why the Import guys never did this sort of stuff is beyond me... but there's no reason why the 3S crowd couldn't start.

If you are really serious about learning this stuff, start measuring parts and publishing your findings, instead of working off rumour and innuendo.

DG

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Originally Posted by Julianvr4

2slow2tedius on 3si...I don't post much here but here is my take on it:

Our rear manifold is a 1n3/4 collected cast manifold, our front is a 1n3/4" half-ass log manifold, feeding a turbine housing as wide as my thumb, using a wheel that was devised in the 80's.
This is why the stock exhaust is ok'ish...we have several restrictions in place, and no matter what you upgrade downstream, it doesn't fix the bunk ass hotside we have (and share with many bolt-on turbos) then if you look at the microscopic internal waste gates we have...another fail. We are supposed to be sending exhaust gas outta that straw hole. Someone needs to cast a bigger hotside.

Adam vr4 running 14b's and adapter plates was able to squeeze out more boost after he got an actual manifold setup.

DSM's and EVO's get a set of hks 272's almost immediately because the are so inexpensive to get their stock cams reground ($200) for us, it's about $400 from Delta camshaft who will copy the lift/duration of the HKS 272's. They also have a much newer front mount, and a BIGGER TURBO. EVOs run 20-21 psi stock on the 16g. They don't have 3 cat converters or limited to a 3" down pipe for 3L of displacement. Packaging constraints are less of an issue for them.



Half-ass proof
My last setup on 9b's and stock cams, I would hit fuel cut before I got any knock at 18-19psi. The car was FAST after I put a fuel pump and a clutch in it. The car weighed 3500lbs with a 1/4 tank of gas. This was on a JDM ecu and I had gone through the combustion chambers with 220g and 320g sand paper to knock down the high spots and smooth out the texture. Nothing to it. Note that I was also running open downpipe the entire time. On 9b's. Stock side mounts. Very healthy engine, perfect compression, NEW OEM IGNITION (coil pack/ptu/plug wires).


This next build that I'm very close to finishing (twin HX35's on a BONE STOCK 6G74) will probably poop out at 15-16psi without meth injection just because of the high compression (making 550whp on 93oct) I've done everything I can to make sure that my biggest restriction is the cylinder heads lol.

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A guy here in Melbourne bought a set of dr750s removed the exhaust housing and used a modified set he made by 9383464 a band around the hot side and machining the exhaust port larger. Haven't heard if he has dyno results for it though. Someone needs to do this and do a back to back comparison.

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Quote:

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Originally Posted by Julianvr4

2slow2tedius on 3si...I don't post much here but here is my take on it:

Our rear manifold is a 1n3/4 collected cast manifold, our front is a 1n3/4" half-ass log manifold, feeding a turbine housing as wide as my thumb, using a wheel that was devised in the 80's.
This is why the stock exhaust is ok'ish...we have several restrictions in place, and no matter what you upgrade downstream, it doesn't fix the bunk ass hotside we have (and share with many bolt-on turbos) then if you look at the microscopic internal waste gates we have...another fail. We are supposed to be sending exhaust gas outta that straw hole. Someone needs to cast a bigger hotside.

Adam vr4 running 14b's and adapter plates was able to squeeze out more boost after he got an actual manifold setup.

DSM's and EVO's get a set of hks 272's almost immediately because the are so inexpensive to get their stock cams reground ($200) for us, it's about $400 from Delta camshaft who will copy the lift/duration of the HKS 272's. They also have a much newer front mount, and a BIGGER TURBO. EVOs run 20-21 psi stock on the 16g. They don't have 3 cat converters or limited to a 3" down pipe for 3L of displacement. Packaging constraints are less of an issue for them.



Half-ass proof
My last setup on 9b's and stock cams, I would hit fuel cut before I got any knock at 18-19psi. The car was FAST after I put a fuel pump and a clutch in it. The car weighed 3500lbs with a 1/4 tank of gas. This was on a JDM ecu and I had gone through the combustion chambers with 220g and 320g sand paper to knock down the high spots and smooth out the texture. Nothing to it. Note that I was also running open downpipe the entire time. On 9b's. Stock side mounts. Very healthy engine, perfect compression, NEW OEM IGNITION (coil pack/ptu/plug wires).


This next build that I'm very close to finishing (twin HX35's on a BONE STOCK 6G74) will probably poop out at 15-16psi without meth injection just because of the high compression (making 550whp on 93oct) I've done everything I can to make sure that my biggest restriction is the cylinder heads lol.

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Sent from my DROID BIONIC using Tapatalk 2

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A guy here in Melbourne bought a set of dr750s removed the exhaust housing and used a modified set he made by welding a band around the hot side and machining the exhaust port larger. Haven't heard if he has dyno results for it though. Someone needs to do this and do a back to back comparison.

Sent from my GT-I9300 using Tapatalk 2