Fanman

In a story on SEMA 2004, they reviewed the kit briefly. I thought this quote was interesting :

"Horsepower instead of the previously promised 303 flywheel horsepower, the new numbers have been lowered a bit. Reason being is that now, instead of holding a consistent 7 psi of boost, the turbo will slowly drop above 6500 rpm to around 5 psi of boost at redline. Reportedly this is done because Greddy has not been able to source suitable colder spark plugs for the Renesis."

I thought this was interesting, and an issue similar to the one the Petit unit had. Let's hope somebody will come out with a new plug for us.

shaolin

Someone email denso or NGK...

IZoomZoomI

dammit, a new issue? how come i haven't received mine yet? Don't rx tuner have one with an article on petitt s/c and other various fi for the 8?

epitrochoid

thats not true unless the next batch of kits includes a boost controller, an internal wastegate alone can not throttle back boost. the kits out right now do not loose boost either.

philodox

Just got my issue today.. Finished reading the article.. too bad these articles in RX Tuner are about 2 months out of date by the time they go to press. Now I need to find myself some cold plugs.. come on all you vendors out there, time to deliver!

rotarygod

If the boost gets lower above 5500 rpm, that is pretty much exactly what happens with the stock turbo on the 2nd gen RX-7. The exhaust housing is a restriction and there is too much backpressure at that rpm. A good boost controller could help this situation out by opening the wastegate a little at higher rpms. The stock turbo on the RX-7 was very similar in size to this one and would max out at a little less than 300 fwhp. This explanation seems like what is happening with the Greddy kit. A turbo that is too small for big power but one that gives it a nice bump in drivable power. If we can run boosted rotaries at 500+ hp levels with tradtional rotary sparkplugs, what is the issue with the stock ones at such a low level? Is it really a plug issue or is it the way in which the ignition system fires them?

philodox

RG, it may have something to do with the way the ignition fires them. Maybe they are fired in a manner where they are much hotter than the traditional way? This could explain why the Greddy kit doesn't touch timing at all. Once someone introduces a colder plug and a new way to control timing I think we can see higher boost levels wiht less chance of detonation with the greddy kit.

dannobre

iTrader: (3)

There is a colder plug NGK RE8A-L One range colder than stock. Come from Mazda Japan

IZoomZoomI

yea i have an extra set of those if anyone wants to buy them pm me ^^^

Kenco

Rotarygod

Philodox already said that his car runs 7psi up to the redline (I think), so at least this shows the turbo can overcome any backpressure after it.

7 psi is not a lot of boost really, I'd be VERY surprise if the turbo could not provide more pressure than that, even at high revs!

My uneducated guess is that it would be able double that psi measurement, only time will tell!!!!!!!!!

Silverarrow

Is the colder plug only leading? Would we need one for trailing too?

dannobre

iTrader: (3)

The trailing plug is almost recessed into the housing. It is not a problem like the leading plug for detonation.

zoom44

i just got my issue yesterday. lot of good stuff in there this month. but to answer an earlier question- the forced in duction "shoot-out" will be in one of the next 2 issues. its not in this one.

Charles R. Hill

iTrader: (7)

The factory trailer is a 9 heat range and the trailers are generally post-combustion except for idle rpm's anyway. My question is in the same ballpark as RG's; what about the ignition coils and such? I am thinking about the XS Eng. ignition amp. Can the factory system handle a jump in operating voltage from 12 to 20 volts? Are the coils sensitive to changes? Can we swap the coils out for some aftermarket versions like the MSD Blaster series? Inquiring minds wanna know!

CRH

SHOWOFF

Ok FI is a new territory for me, so what do you mean by a "colder plug range". Are you talking about the operating temp of the plug or the level or size of the spark?

silverx8

What about a boost "cooler".

Use overboost to pressurize the intercooler, say 20 PSI. Yeah thats right get the air good and hot. Put a pserrsure regulator on the intercooler output to drop the pressure and temperature to about 7 to 10 PSI at below the intake temp, say a 20 to 30 degree below inlet temperature drop. This would increase charge density and reduce the tendency to knock.

rotarygod

I don't follow you. How that could that possibly work?

Charles R. Hill

iTrader: (7)

For a full description on plugs and heat ranges go to NGK's website. They have a great explanation on the several things that spark plugs do besides spark.

CRH

army_rx8

no kidding..i woudl like to know as well

Richard Paul

iTrader: (5)

I think he is trying to build an air conditioner.
That runs for free.

rotarygod

I get it. Kind of like perpetual motion or cold fusion. That should be easy.

Too bad working a turbo harder to get 20 psi and then bleeding 10 of it off is WAY more heat into the system than you originally had at 10 psi. I still don't know how a bleed valve on the outlet side of the i/c would change the intercooler. The air is still entering it hot which heat soaks it much faster and air is still leaving it. The only thing this did was to give you half the boost after the intercooler. On top of that, the half you do have is still as hot as the amount before you bled it off. I can't even figure out the inital logic or way of thinking on this one. Not a single part of it makes any sense. Oh well.

Charles R. Hill

iTrader: (7)

Yeah, since he mentions going colder than ambient it sounds like air conditioning, of sorts. I ponderd a freon-charged liquid-to-air I/C once but realized that the compressor would need to be rather huge in order to have enough BTU capacity to remove that kind of heat. Almost a diminishing returns kind of thing.

CRH