Rb26 And Higher Compression

[zebra]

I was going to run WMI, but was told but so many people not to, I am kinda glad I didnt now, you are right water stays cooler for longer, but once it warms up it is almost impossible to get cold again with the size heat exchanger you can fit in most cars without lots of cutting etc.

[STATUS]

It'll be a water to air intercooler. The water stays cool for a fair while after u slow down. 12psi is pretty low tho. Hottest days here in Tas are about 35 degrees at the very most and i won't have air con or anything. Also I'll be running a Haltech with air temp compensation set up to run richer once air temps get too high for my liking.

had nothing but trouble with W2A they heat soak way to much, i even tried a 600x400 radiator and an extra reserve in the boot to slow down heat soak. Under bonnet temps just kill the benefits... if you could mount the w2a in the cabin away from under bonnet heat it would be great.... just not practical.

[bradsm87]

There's a LOT of shit out there in terms of crap water to air intercoolers. I think that crap (75% of the stuff out there) gives it a bad name. I'm gonna give it a go in what i think would work with a massive overkill of radiator area (multiple radiators). Also the huge total surface area of the fins inside the intercooler is hundreds of times more than the outer surface of the heat exchanger. i can't see how it'd be affected by under bonnet temps any more than it does to intercooler piping. The thought of 30cm of total piping length plus an intercooler half the volume of a conventional fmic is too good not to at least try. i want near instant throttle response and full boost at about 2500rpm!

[Sidwysracr]

increase to 10:1 on pump your crazy... on E85 then your talking.

AEM ecu is awesome providing its the version 2. My favourite plug in ecu atm behind PFC.

crazy? maybe 11:1...or even 12:1 with E85... many can do all day with those comp ratios.

[Jap_Muscle]

What advantages are there by having a higher comp compared to a lower one? And vise versa what are the downsides?

[bradsm87]

Higher comp is more efficient but too much with not good enough fuel means detonation.

Higher comp will make more power for the same level of boost, all else being equal.

Higher comp will bring boost on quicker.

Lower comp allows running more boost without detonation on the same fuel.

[STATUS]

I read a lot about -9's and -5's. -9's fit a perfect to street car for what most people say, but once it reaches the upper rpms it runs out of it's puff, this is where the -5's shine.

Here's a dyno graph with a comparison of -9 and -5's, the taller line is obviously -5s, but you can see that the -9's match the description as above.. and notice that the -5's are only 300 rpms behind. But notice the torque curve... even though not sooner, but it allows you to say in gear longer before it dives down.

They follow nearly nearly identical paths on the up climb (the difference noted above), the -5's does it more efficiently. I plotted both the -9's and -5's compressor maps. Like I said 77% over 74%, less hot air the better. Tuning and cams can make the -5 spin sooner.

I am after a track build, what ever gets me around the corners faster and have enough top end to keep up in the straights. Raising CR will allow more off-boost power, which for a tracker that means a fatter power band to be used. My differential ratio is 4.363, so naturally in the higher rpms...with this...it would make the -5 spin sooner...and in the end I would have a lot of top end too. A bit of tuning can make the -5's respond sooner as well.

i call bogus on the comparo.... ramp rates are not the same between runs.... i have the same dyno and can tell you the only way to split the runs like that is to either run a 4sec start delay to build boost or increase the ramp rate in seconds..

Power correction is in DIN which over inflates the power by a bit too (about 10-15rwkw @ that power)...

[STATUS]

There's a LOT of shit out there in terms of crap water to air intercoolers. I think that crap (75% of the stuff out there) gives it a bad name. I'm gonna give it a go in what i think would work with a massive overkill of radiator area (multiple radiators). Also the huge total surface area of the fins inside the intercooler is hundreds of times more than the outer surface of the heat exchanger. i can't see how it'd be affected by under bonnet temps any more than it does to intercooler piping. The thought of 30cm of total piping length plus an intercooler half the volume of a conventional fmic is too good not to at least try. i want near instant throttle response and full boost at about 2500rpm!

we were using PWR kits.

[bradsm87]

we were using PWR kits.

I REALLY hate putting down Australian companys but that is exactly what I was talking about. The core design is terrible. The ratio of coolant to charge air area is way wrong and tube and fin intercoolers with the charge air going through the tubes like in an air to air is very inefficient in a water to air core.

Best is a very fine bar and plate design with lots of fin surface area. Also the coolant passages don't need to be anywhere as big as the air passages because the coolant can transfer heat much easier than water. This means more area for the charge air in the same physical dimensions.

Plazmaman or ARE are the way to go.

I agree that getting the heat out of the water is the hardest part and a huge challenge. I don't even know if it'll be any good but i'm willing to take the risk. I'm only aiming for 220-240rwkw and the car has heaps of frontal area to use for the radiators. (one in the middle where a FMIC goes , fully ducted and one off to the side where an oil cooler is usually mounted)

Edited December 20, 2010 by bradsm87

[STATUS]

I REALLY hate putting down Australian companys but that is exactly what I was talking about. The core design is terrible. The ratio of coolant to charge air area is way wrong and tube and fin intercoolers with the charge air going through the tubes like in an air to air is very inefficient in a water to air core.

Best is a very fine bar and plate design with lots of fin surface area. Also the coolant passages don't need to be anywhere as big as the air passages because the coolant can transfer heat much easier than water. This means more area for the charge air in the same physical dimensions.

Plazmaman or ARE are the way to go.

I agree that getting the heat out of the water is the hardest part and a huge challenge. I don't even know if it'll be any good but i'm willing to take the risk. I'm only aiming for 220-240rwkw and the car has heaps of frontal area to use for the radiators. (one in the middle where a FMIC goes , fully ducted and one off to the side where an oil cooler is usually mounted)

yeah we gave up on them, ran a decent 115mm tube and fin cooler and car never ran better.... (bar and plate was just too heavy).

[rob82]

Higher comp is more efficient but too much with not good enough fuel means detonation.

Higher comp will make more power for the same level of boost, all else being equal.

Higher comp will bring boost on quicker.

Lower comp allows running more boost without detonation on the same fuel.

Increasing comp also reduces EGTS when running on E85.

[bradsm87]

Increasing comp also reduces EGTS when running on E85.

Both those things will reduce EGT by themselves. Both even better.

[Rolls]

about 9.7:1 and 18psi would be the highest I'd go on pump 98.

I know a guy who runs an 11:1 SR20 running 23psi on E85!!!

running big cams means you can get away with higher static comp ratios as the dynamic compression ratio decreases as well, keep this in mind.

[bradsm87]

running big cams means you can get away with higher static comp ratios as the dynamic compression ratio decreases as well, keep this in mind.

They're HKS 264's. not massive. it's pretty much all in the fuel in this case.

[Rolls]

They're HKS 264's. not massive. it's pretty much all in the fuel in this case.

yeah I was talking generally, but even 264s will decrease the dynamic compression slightly.

[zebra]

Adjusting the cam timing will affect the dynamic comp too

[Sidwysracr]

Bump for nismoid

[bigmikespec]

Digging up an old thread... has anyone taken the time to work out the dynamic compression of a stock RB26?

[bigmikespec]

http://www.kb-silvolite.com/calc.php?action=comp

Here is the calulator I was going to use but I do not know the "Deck Clearance (in.)Note: Neg. nubmer above deck, Pos. number below deck" if anyone can help?