Tudor

Hi All,
I'd like to turbo a Renesis engine myself. All thought I have very good fabricating resources (I'm tech. director and race engineer of professional F3 team) I have no experience with rotarys. Our engine guy is great with NA piston engines but he has no experience/knowledge on FI.
I have a bit of advantage over regular RX8 owner in regards that I'm less restricted with packaging because I can design chassis engine area together with engine and FI installation in mind - this gives more freadom.
Using stand alone ECU (capable to control flybywire throttle) eliminates many of engine management problems.
There are some very knowledgable people on this forum and I'm really looking for some advise from them (sorry for not naming anyone in persone but that could hurt thos that I would miss due to my limited knowledge)

Questions that I have atm:

1) What would be best choice of turbocharger itself? My goals are greedy - 400+ at the flywheel. Minimum lug... I can live with boost coming in no earlier than 2500 - 3000RPM but nothing may be more annoying than to wait for boost after upshift. Good mid range torque. In fact I'm not even sure that all this is possible at once.
I have to say that money is always an issue but I want a good ball bearing, water/oil cooled turbo. So question is which exactly model, from which manufacturer, from which source I should choose?

2) Another question that is really bothering me is why the hell turbo?!?! Shouldn't I go for those twin screw or axial flow supercharger??? I know that this is a very THEORETICAL question but I just can't help it poping up again and again in my head.

Thank You
Ted

PS: Sorry for my English

guitarjunkie28

35r with a .82 t4 hot side.

Tudor

Stickmantijuana,

Yep, I'm serious. I'll dig a couple of team pictures on monday when I get back in the shop.
Thanks for your suggestion on GT35. 20B is nice but it is roughly 30% longer and heavier.

guitarjunkie28,

Long time no talk... Sorry for being silent for so long. Short after I talked (email) to you I was hired by that team and from than I was simply burried with work. Now (offseason) I'm restarting my project.

Thanks very much for your detailed suggestion.

IS this what you mean? -
- http://www.himni-racing.com/index.ph...products_id=55

Where would you advise to purchase it? Does 1280$ sound like a right price?

Another question is GT3582R a best and only choice? Would it be too big/luggy?
It seems that in all of the kits available people are going for different turbo's T3, T3/T4 hybrid etc.
At what RPM I should expect that it "comes on"?

Thank You
Ted

Tudor

My next question:

How important is intercooler "brand"? It seems that I could find some units very cheap - http://cgi.ebay.com/ebaymotors/Front...1517QQtcZphoto

Or should I go for something like Spearco which seems to be way more expensive?

How do I choose the right size? I can probably do the math myself (if it's similar to choosing radiator size for an engine) but what result should I look for? What charge temperatures are expected and how much I have to reduce it?

If someome simply says that this exactly size/type of intercooler will be good enough that would help

Thank You
Ted

unreal89

I have done some research, and I heard ebay intercoolers and wastegates work fine. But because there are many different knock offs, Google some one who is satisfied with a certain product from ebay, and buy from that exact same ebay seller. And stay away from ebay knock off BOV's.

This is based on my research, not my personal experience.

But remeber, theres always a bigger risk from ebay knock off parts. If you want trouble free, buy name brand.

Tudor

Thanks Stickmantijuana,
As far as I know Mazsport is using T3/T4 T04 hybrid turbo, they don't name turbo's maker. At list I didn't find it myself.
While Scotts kits are definately among the best on the market, they cost from 8000$ and UP including int-X. I'm starting to feel positive that I can fit well within 3000$ with VERY good parts selection. Without ECU but I can not count it in turbo cost as I have to buy one with or without turbo.

As for your thoughts of race engineers knowing much about engines. I don't think that many do and I know some with vast F1, IRL, CART, NASCAR experience. Every even small team would normally have a separate engine department no metter if it consist of only one engine guy. Race engineer will normally only deal with engine guy on the gearing issue and fuel usage. (This is very much "generalised" but true) He will than 90% of his time work with the various aspects of chassis setup (aerodynamics, mechanical grip etc.) all aiming at one ultimate goal - to make maximum use of those 4 little rubber patches that connect the car to the road.

Thank You
Ted

Tudor

Stickmantijuana,
It is allmost imposible to give any advise without having all the neccesary info on your car - sprung and unsprung corner weights, suspension pickup points and springs/shocks, sway bars motion ratios etc., etc. As I said I don't own an RX8 and my project is not an RX8 chassis so I know nothing about it.
I can only speculate using some rules of thumbs. 20B will definately give great results in straight line acceleration. How ever as it is longer and heavier it will definately stress front tires more. This will add to understeer and RX8 being a mass production vehicle is already biased towards understeer. Strangly but this will most likely lead to exit oversteer - this happens very often with car which understeers on corner entry and mid corner. Due to turn in US driver will normally add more steering wheel lock and past the apex when he starts to unwind the steering wheel and car derolls, fronts finally find grip but being turned too much car will snap to oversteer. What I'm trying to say installing 20B will definately change weight distribution to worse.
But all this will only apply in case the car is driven close or on the limit of tires adhesion - i.e. on the race track. On the street normal driving is only using about 40 - 45% of tires capability (and anyone driving on the limit on public roads is posessing danger to others) so adverse effects on handling will not be felt that strongly.
As to high speed stability I would suggest going for a good and tested rear wing. You would not need draggy two elements setup but single element at conservative AoA will work fine. This will have great and increasing effect at speeds over 80 mph.

There may be some other issues with 20B installation - like steering rack position - will it be neccesary to move it? If not than fine but if yes I suggest that you find people that know what they are doing. A car with excessive bump/roll steer will be very unpleasing and difficult to drive fast - even on the straight line.

Sorry for being unable to really help.

Now back to my turbo choice problem - is GT35 one and only best solution? When ( what RPM) I should expect it to "come in"? How would it feel accelerating out of the corner? All I'm trying to ask is how luggy it is going to be?

I would love to hear opinions of RG, Mazsport Scott, Mazdamaniac and other knowledgable people from this forum.

Also would anyone help me with intercooler choice - size and maker (Here I want to go as cheap as it is practical without compromising performance and reliaility)

Thank You
Ted

Tudor

Thanks Stickmantijuana,
I contacted Evilmiata and had some nice comments from him.

Cheers
Ted