Is my dream possible? (goals for rb25det)

[Snarlynx]

OK... it's like this. The rb25det swap is getting more and more popular and so I'm upping the rate at wich I'm moving ahead with the project ( don't want the rise in price and lowering in availibility like the sr20det). but before I do I want to know if this is possible with the rb25det.

1) Low 12 second (12.3-12.0) 1/4 mile times in great but "streetable" tires.

2) retaining at least a high fifty/low forty f/r wieght ratio with perhaps some trick part placment and even the amount of gas in the tank.

3) a smallish, very responsive "autocrosseque" turbo that will allow just enough power for the low 12 second 1/4 mile times.

4) no upgraded internals.

If this is possible, what kind of HP would I need, parts I would need and even suggestions for a turbo that would fit my needs.

All responces are aprieciated.

And don't tell me to search. All I get is a bunch of posts telling me to search. :|

[spec-v5150]

The info is there. Anyhow I believe that NIght said he was running twelves with stock everything. I don't know the exact number. I would assume you could hit twelves too. I dont know if they will be that low. I havent researched the 25 much

[TropikalSX]

If you are autocrossing I would go with a turbo KA24DE. It will easily have more torque than horsepower and it can run 12's easy with just spending a grand on new internals with a T3/T4. You would spend a lot more doing an RB25 swap and KA engines are a dime a dozen. IMHO I would do a RB25 if it was for circuit racing or drag racing since it will hold bigger horsepower numbers reliably.

Go with a turbo KA and upgrade your rear end gears to 4.9 which will cut a whole second off your time =) With traction you should be at an 11 sec 1/4 easy and run circles around people at the autocross events.

[chachi longshot]

A T3/T4 sounds a little big for autocrossing. I'd think that would take a lot longer than he's looking for for spool up.

[Snarlynx]

I probably won't autocross much. I just want the most responsive turbo possible for what I want it to do. I want a balanced car. One that can keep with a lambo ( in theory :pface ) in a strait line, hang with a rx-7 in the twisties and look great while doing it (s15 front end)

I hope this clears things up and thank you for your responses.

[TropikalSX]

You can do a few things good or do one thing great..

[apex_7]

Night ran a 12.6 w/ a clutch, full exhaust, intake, and almuminum driveshaft if I remember correctly. I'm sure you could strip it out and up the boost to obtain 3 tenths more

[Snarlynx]

so, with only what... 260ish at the wheels is good for mid 12 time slips?

wow, I wonder what grumpy (with the 350 hp at the wheels before nos) can do....

[chachi longshot]

You sure he ran that time with that setup? I know he at least had an LSD on there. And I'm pretty sure he has a T3/T4 turbo on there, not sure if he had it on there at the time of that run though.

[spec-v5150]

that is what he said......

[dcdrifter]

What is this crap about being able to run 11's with a t3/t4 with a ka engine, with $1000 in internals. You must be dreaming!!

[illspace]

you dont even need internals to run 11s with a turbo KA, and yes a t3/t4 will do it pretty easily...

[toki]

and a gutted civic with an engine from an Ingetra LS runs 12's.

[mmdb]

In regards to #4 yeah you will have to upgarde the internals if you plan over 300 hp. #1 and #6 piston rings go bad around that hp. The engine runs at 9.0/1 air fuel ratio which isn't exactly turbo friendly. How do i know?

http://www.skylinesaustralia.c...00313

Those guys have the r33gts-t in their skyline, which we only dream of getting here legally, and at a decent price (excluding motorex). I guess the problem with the o-rings busting on the pistons could be mistuning, or high compression, but still... I'd expect more from an rb.

[Nathan]

HUH? 9 to 1 air fuel ratio would be so rich it'd be smoking all the time...it runs much closer to 12 to 1. As for only taking 300hp, that's crap...search around more on skylinesdownunder and you will notice that 450bhp, or approximately 390whp without any major problems is the most often quoted safe horsepower level for an RB25.

[mmdb]

just sayin' nathan. Given the time you get these engines they could be over beaten, sittin' in a junk yard rotting, whatever. Just expect to rebuild in the worse case scenario. Although the rb25det rests in the image of the skyline, the most iconic car of japan, it's only an engine.

About the 9.0 to 1, i meant the compression ratio. Sorry for the mix up, midterms during the summer are not fun.

[Nathan]

Its ok...if I came off as harsh its because 8 hours of fixing excel spreadsheets isnt fun either. But yeah, the compression ratio is a little high although I dont see that as a big problem with proper tuning. One thing I'm contemplating is a thicker headgasket to bring it down a bit I was talking about an engine in excellent condition anyway, one that compression checks well and has no mechanical problems or significant wear. Your right about the nature of an imported engine, we dont know the history at all...however, I would not hesitate to lean on an engine that passed a leakdown and compression test with flying colors and that I had visually checked out fully. I plan on dropping the pan, pulling the valve covers, spark plugs etc...I will check every combustion chamber, check out how everything looks before even putting the engine in my car

[mmdb]

No offense taken That's a good idea doing all those things. I'm thinking about lowering the compression ratio with the help of new pistons, but that brings me to the issue of sourcing them and/or other parts. But like nathan said, if you can find a reputable seller, and if they're willing to do some compression tests or has done them, by all means you can build one bada$$ motor.

[Nathan]

Well, no matter who you buy it from...I'd still recommend doing a compression test YOURSELF. Who else can you really trust? After about 350hp I'd think about going with some forged internals...I have no idea how strong the stock crank is...I'm sure it's strong but I bet the RB26 one is better and it bolts in...then you could get some forged rods and .030 over forged pistons and be in business for a LOT of power.

[Snarlynx]

Way too expensive. forged and college student doesn't go together. working full time is already killing me, any more and I'll keel over and die. I know power doesn't come cheap but I'd be happy with ~350whp (epesially if that'll get me to the low 12's) over the next two or three years until I graduate....

so like SCC said, the next step is "experiment on your own or copy a really nice set up"

I think I'll copy grumpy and mack's set up as much as resorces and info allows.

[meggala]

your goal is achivealbe the one thing to monitor is your af ratio your injectors are only good for around 400 with a good fuel pump on an rb 25.Remember that an s-afc or emange are a good ecu to use on these motors.for budget results t3/t4 should be ok.detonation is the biggest killers of these motors.meggala

[Snarlynx]

thanks. I will look into a s-afc, espesially sinse the s-afc II is coming out soon if it already hasn't and that will drop them in price....

[Nathan]

I've seen them for under 150 on ebay

[s15nc]

if you want to know what kind of HP it take to make certain runs check out http://www.dsm.org/tools/calchp.htm things to remember s14 2750lbs, S14a 2850lbs, s13 2650lbs, don't forget to add your weight and an extra 50-100lbs for the rb. Now you can make a lot of that up if you strip weight out of your car as well when you race. Lastly don't forget that is a theoretical number assuming perfict traction so their hp numbers will be lower than what you will need to do that kind of time because your tires will slip.