thehelix112

Started this thread to stop more of a hi-jack from this thread: http://forums.hybridz.org/showpost.php?p=712084&postcount=28 In response to I am not sure what you mean about mounting the calipers `low on the spindles'. Are you just talking about the 5/7 o'clock mounting position? Some random thoughts: while you are correct in that this lowers the centre of gravity of the strut assembly, as this is sprung, it does not affect the centre of gravity of the car at all; and thus its only affect is in determining the magnitude of the moment placed on the chassis by the strut assembly when in a turn. This moment on the inside wheel will attempt to pitch the car undesirably (out of the corner), but on the outside wheel it will attempt to pitch the car into the corner. I would hazard a guess that these two moments would all-but cancel each other out, and you're left with no impact at all. Unless I have missed something incredibly obvious. This is something I have never completely understood, and am keen to do so. Though it might be better in another thread? Dave

bj, I am not sure what you mean about mounting the calipers `low on the spindles'. Are you just talking about the 5/7 o'clock mounting position? Some random thoughts: while you are correct in that this lowers the centre of gravity of the strut assembly, as this is sprung, it does not affect the centre of gravity of the car at all; and thus its only affect is in determining the magnitude of the moment placed on the chassis by the strut assembly when in a turn. This moment on the inside wheel will attempt to pitch the car undesirably (out of the corner), but on the outside wheel it will attempt to pitch the car into the corner. I would hazard a guess that these two moments would all-but cancel each other out, and you're left with no impact at all. Unless I have missed something incredibly obvious. This is something I have never completely understood, and am keen to do so. Though it might be better in another thread? Dave

Please do scan the page. My copy is in Australia. One thought on using diesel-application parts, it will burn. The temperature in a petrol-engine'd exhaust manifold will be significantly hotter than the temperature at god-knows-where in a diesel exhaust system. Dave

283z, I would not be juding any engine based on ONE (potentially poorly) modified example, and I definitely wouldn't be comparing a 6-cylinder thats almost 50% more of the displacement with a 4-cylinder. And as for tuning a(NY) forced induction engine with a (most likely old and out of calibration) narrow-band oxygen sensor; well it sounds like a first-class, thorough and trustworthy job you do there. Dave

Its exactly this pissing competition that I hope the aero-results from bjhines & crew put a stop to. I don't hold it against you guys responding to the question, just that the question itself is pointless and subjective (because we have no data we can use) and I hope that hard objective results will answer all such future questions. Dave

Best motor swap for you hey? Maybe if you gave us a little information about yourself we could help? Please start the list with name, credit card number, expiry, and available balance. Dave

Hehe, my zed came with a tow bar (and yes I did use it). It didn't look that heavy until I undid the last bolt and it fell on my chest.. then it felt plenty heavy (about 50 lbs). Dave

I think its an interesting idea. The turbo came from a VG30DET engine you say? If so, good find, they're nice little turbos, and a pretty good match for the L28ET. I would be careful to heat sheild the plugs from the turbine housing. Good luck, Dave

Maybe its the academic in me, but I feel obligated to cite that article in #41 as from Mark Ortiz at The Performance Tech Forum/Board Damn good read btw. Dave

zeiss, Cams for STOCK turbo engines tend to be small and have limited overlap, because said engines also tend to have small restrictive manifolds and turbochargers. If you put a cam with large overlap you get reversion of the charge out the intake. In short, there is no rule that says turbo engines must have little/no overlap, its just a matter of matching the cam with the rest of the engine setup. Dave

magnadyne, With all due respect, it sounds to me like johnc has done a lot more reading on this topic than you. Your comment about increasing normal force (weight/aerodynamics) is true, up to a point. Milliken & Milliken have several examples of tyre load sensitivity charts, which is what you are talking about. When you add loading via weight, you increase not only the force the tyre can generate, but you increase the amount of force that is required to achieve a given acceleration. The problem is that the force required increases at a linear rate, but the increased force generated (as per tyre's load sensitivity) is not-linear, and has limitations. I dislike talking about `grip' as well. What we are talking about is the ability of a tyre to exert a force on the car's suspension components to produce an acceleration. Dave

John, Tim needs larger than 72/77 ld/hr injectors because his turbo is capable of ~850hp. Dave

Ron, That makes sense in theory. I would also guess that it would not be a significant factor in the S30. Oh and bonnet vents should all be like blueovalz's. Dave

Tim, Good point re longer burn meaning more work, meaning lower EGT. I've never played with an EGT gauge, but that makes sense to me. It also makes sense that blowthrough would result in higher EGT due to burning in the exhaust manifold. A simple way to decrease blowthrough is to reduce the turbine housing A/R. This creates more of a restriction to flow, and will increase exhaust manifold pressure. Plus you get the added bonus of better response. Maybe a 1.01 housing just to test? Dave PS. I am sick, so I apologize if that doesn't make sense.

I'm with veritech, reduced back pressure should mean reduced EGT (PV = nRT), and more timing should be increased EGT (the charge has longer to burn so tends to do so more thoroughly?). Re boost creep, remember that most commonly occurs when the wastegate cannot vent from the amount of gas coming out of the engine, down to the amount of gas needed to maintain the compressor PR. If you increase PR, you need to vent less gas, and I think the problem will go away. Best of luck with it all, Dave

Care to elaborate on that some more? I don't really see how the temperature of the bonnet would affect the boundary layer. Dave

Do you have an approximate cost? What grade alu were you thinking of? Dave

I'm intrigued by your comment on heat buildup. Care to expand? Dave

How many years into your PhD are you? Having just finished mine, I would suggest you steer clear of here http://phdcomics.com/comics.php for sure. Your project sounds interesting. More details please. It would seem that self-tuning is entirely dependent on the resolution, accuracy and calibration or sensors. It that still manually controlled? I would be interested also to hear the research questions you aim to answer? Dave

I say you implement a boost limit randomizer for the road course. Keep the driver on his toes. Care to get a free plug and tell us some features of your ECU? Dave

1. Yes, as the turbo (should) draw air through the MAF/AFM, the engine will be aware of the increased air being ingested. The trick is that the MAF/AFM will have a limited resolution, after which it is `maxed out', and it cannot measure increased flow. E.g, say your AFM can only measure up to 10lb/min of air, if you are actually ingesting 15lb/min, you are going to have a problem. 2. You can substitute different injectors assuming they are the same impedance, plug and shape. How well the standard ECU adjusts is very much dependent on how old it is. I wouldn't be expecting miracles. The std nb O2 sensor is not good for much aside from saying `right/wrong'. 3. Don't use a universal harness as far as I know, but then I have only seen ones that use a Bosch type plug: 2 pin female - 9 122 067 011 New Part Number Now 1 287 013 003 Dave

That crank is a pretty good buy by the looks to me. Look at it again. 1. Its fully counterweighted which means its a custom unit. 2. If its a custom unit its probably forged because well, why else would you bother? 3. It already has cross drillings. 4. If its been built properly its probably already perfectly balanced and perfectly straight. If I had money RIGHT now i'd buy it. Dave

Looking damn good Tim. Let us know when she cracks 600. Dave

Excellent question. For forced inducation applications I would hazard a guess it is to do with a few things. 1. Equal length runners. This is much more important for an intake manifold (IMHO) as unequal length intake runners can lead to differing ram effects at differing RPMs. 2. Packaging. Given the requirement 1, packaging an intake manifold with equal length runners that does not use a surge tank (and provide a simple, easy, place for the air flow to be controlled at) with a single T/B would be quite tricky. 3. Single T/B or Cost. It is much cheaper to put a single t/b on a car and call it a day than it is to provide individual t/b setup with equal length runners. 4. Throttle response. In a performance application, as you are talking, you want the t/b(s) to be as close to the head as possible for throttle response. The interference of the butterfly's (assuming you have them), reduces the ram effect. In N/A applications you do have equal length runners in most individual t/b applications. Dunno if that makes much sense, I'm tired. Dave

That page has misapplied those formulas for the reason Clifton hinted at. He has mapped a straight line from 20% at 1:1 PR, increasing in pressure ratio linearly to his `knee-point' where full boost is reached. It doesn't happen that way. Show me a T61-1 equipped L28 that will make positive manifold pressure at ~1300rpm (~20% redline) and 20psi by 3250. My GT35R (ball bearing, and smaller than a T61) has only JUST gone positive pressure by 3250 and 20psi isn't seen until 4500 or later. And, the increase in boost/PR with revs is not likely to be that linear. In short, a highly simplistic view of things, and not worth the electrons that were used to deliver it to you. Dave