WI good for high comp turbo cars?

[austinaltezza]

a high compression ratio car combined with boost over 10psi would spell disaster but am wondering if WI injection will help prevent engine grenading.

lets just say a S2000 boosting at 1x psi

[hotrod]

It may be the only option to allow you to run that sort of boost.

If it can keep an 8.5:1 compression ratio unlimited air race engine alive at 50 + psi boost it should work for you.

10 psi boost @ 10:1 compression ratio is about the same as running a 17:1 compression ratio.

Larry

[Charged Performance]

A well thought out and implemented system will certainly help with suppressing detonation - there can't be any skimping on monitoring and response aspects. Also at some point detonation suppression only goes so far - extremely high cylinder pressure applications are going to require something more than a bolt-on and tune. You really need to blue print and bullet proof the components for the pressures - and make very sure your lubrication system is up to the task.

[fperra]

I've been running 9 psi on my s2000 for the last 8 month with the 2d system and no detonation problems.

[JoeB]

I have a 99 Toyota Solara with a 3.0L V6 1MZ-FE that has 10.5:1 compression running a TRD roots type supercharger. The pulley size I am running is nominally a 7psi pulley. I've been very concerned about giving it too much. I upgraded the fuel system from 250cc stock injectors to 318cc and a Walbro 190LPH to replace the stock 90LPH fuel pump. I use a Split Second FTC1 to control fuel and timing. I was not detecting any knock with that setup.

It's really good to see others doing similar because I'm being told I'm crazy. I can't find a good solution to reduce compression at a reasonable cost. I can't find anyone that makes thicker head gaskets for the engine and the only other way I know is to use low compression pistons and that whole job is just too cost prohibitive. SO, I installed an Aquamist 2d system in hopes that it would allow me to boost more safely. My end goal is to take it to 10psi. However after I installed the WI, I noticed boost pressure in the sc housing rises to around 10psi at red-line. I'm very certain I don't have it tuned right. I'm trying to read and learn exactly what I need to do. I've already read a ton on this forum and some of the references. Thanks for the note hotrod, it's reassuring to hear you say this is possible. Also, Ed for the caution about monitoring although I'm still trying to figure out good safety mechanisms. I was told the high boost pressure might be due to the lack of ability to scavenge the exhaust and headers would help but I already have a complete high performance exhaust system.

What should I watch for as I try to increase the boost? I have an EGT with the sensor mounted very close to the top of the headers. I read that the temp should be around 850 degrees and preferrably under 900. Then other places I see people saying under 1600 degrees. I'm a little confused there. Any help? One thing I am going to try to do is use stronger bolts in the head. I've heard the stock bolts in most cars are weak and with the high compression, I risk blowing the head gasket.

TIA -JoeB

[hotrod]

Where are you injecting the water?

Injection in front of a roots type blower will actually increase the effective boost. The water cools the intake charge, (increases the volumetric effeciency of the blower itself). In some cases they have documented that small amounts of liquid passing through the blower tends to improve the blower seal.

Injecting after a postitive displacement blower does not change the effective boost it only lowers the charge air temp. In the special case of a postive displacement blower, the mass flow is determined by the blower displacement and its speed. Once the air is past the blower it is a fixed amount and if you cool it you will actually drop the boost level. A turbocharge on the other hand is a constant pressure, varible flow device, and if you cool the charge after the turbo the boost will remain constant as it will simply flow more air at the same pressure.

Larry

[JoeB]

Thanks Larry, I am injecting the water just before the throttle body, after the MAF. Can you help me out with the last paragraph, what to watch for as I increase boost with my high compression? Thanks -JoeB

[hotrod]

I read that the temp should be around 850 degrees and preferrably under 900. Then other places I see people saying under 1600 degrees. I'm a little confused there. Any help?

That is simply the difference in temperature scales, the numbers near 800 -850 are in degrees Centigrade, and the numbers near 1600 are in degrees Farenheit.

As far as what to watch for, --

Be careful tuning by EGT, one of the signs of detonation is a sudden DROP in EGT under high load. It sounds counter intuitive, but dropping EGT numbers are not always good. During detonation much more heat gets passed to the piston tops and cylinder heads due to the detonation wave stripping off the thin insulating layer of gasses. This actually drops the EGT. so be sure you know why your EGT's are going down if it happens under heavy load.

I would strongly suggest you learn how to read plugs for signs of detonation and while tuning read ALL your plugs every time you make a change until you know where you are. During detonation the spark plugs will show very small black or white spots on the tip of the plug. You will need about a 10x magnifier to see them. They will be very small balls of melted aluminum (silver specks) or bits of carbon or cast iron (black or dark purple specks) that gets blasted off the piston tops, or cylinder heads during detonation. The term "salt and Pepper" is used to describe this sign of detonation.

As far as head bolts/studs. If your engine type is known to need upgraded head bolts or studs you should get ARP bolts/studs. They are generally considered the best you can buy.

Larry