Turbo to produce 400hp at wheels?

[rbs13]

apparently lag freee... its a t67 25g.. meant to be perfect match for sr.. sharp ramp of boost at 3500, it made 288rwkw on 1.5bar with 98oct fuel, power fc, blitz injectors (850cc for those interested) 300zx meter, 1.4mm head gasket (this is where a rb20 is good.. low comp.. higher boost!!! IMO) step 3 cams from hks and a tomie solid lifter kit, hks cooler. cool hand luke has a hks t300 and his car makes 300rwkw with boost at about 3500.. seems REALLY strong and cant really notice lag.. although this is sr crap. im sure it wouldnt be too far from a rb20.. alreading having low comp - more boost.

[Sydneykid]

Hi rbs13, I alweays work out the average power from 3,000 rpm below the cars max rpm. For example,

At 7,000 rpm it has 300 rwkw

At 6,000 rpm it has 250 rwkw

At 5,000 rpm it has 195 rwkw

At 4,000 rpm it has 93 rwkw

That's an average of 210 rwkw.

Compare it to this car;

At 7,000 rpm it has 260 rwkw

At 6,000 rpm it has 240 rwkw

At 5,000 rpm it has 200 rwkw

At 4,000 rpm it has 170 rwkw

That's an average of 220 rwkw.

Which car do you reckon is faster?

[rbs13]

so your saying ditch the rb20's cause they just wont spool a turbo making worth while power? on a highway race (lets say they are legal) your going to drop into 2nd, i think you would have high enough revs to have MR. bloddy big turbo ready.

[rbs13]

i know that, but it also depends how you drive, what you want the car for.. the guy who started this thread should of said i wanna use it for drags.. now then i would of said your better off with a smaller turbo so your on boost longer and therefore quicker or going a bigger motor. but he's just said i want 400rwhp witha rb20.. what turbo should i use. im not EXACTLY sure what turbo he should use im just saying a t67 should work alright.. maybe try going gt30.. ???

[rbs13]

on the street car 1 would be quicker.. mite lose for a second but i think the power it makes at 6000 - 7000 should make it pass car 2. but on a strip car 1 would have the trophy.

[Sydneykid]

Sorry maybe I didn't explain it very well, let me have another go.........

You rev car to 7,000 rpm on 1st gear (making 300 rwkw)

You then change into 2nd gear

RPM drops to 4,000 rpm (making 93 rwkw)

You then accelerate through 5,000 rpm (195 rwkw)

Then through 6,000 rpm (250 rwkw)

Onto 7,000 rpm (making 300 rwkw)

You then change into 3rd gear

and the process goes again.

Meanwhile the other car had;

170 rwkw (when you were at 93). That's a 77 rwkw advantage

200 rwkw (when you were at 195). That's a 5 rwkw advantage

240 rwkw (when you were at 250). That's a 5 rwkw disadvantage

260 rwkw (when you were at 300). That's a 40 rwkw disadvantage

Add it up, 77+ 5 - 5- 40 = 37 rwkw advantage to him.

Multiply that for 2nd gear, 3rd gear, 4th gear, that's a 111 rwkw advantage to him. How much you gunna loose by?

[Roy]

I know the article your referring to and im guessing the statement amost lag free is referring to the actual definition of lag, not the meaning commonly used on this forum.

My car is just hitting 8psi at 60km/h in 2nd. Anyhigher rpm and slow corners like turn 2,9 at EC and final turn at Wakefiled will become an issue.

I have been in an S13 with SR20 ad a TD06-20g setup and it wasnt making boost at hose revs, then again it didn thave the head/valvetrain work that T67 SR has.

[rbs13]

i think the cam gears bring lag times down a bit.. but then again whats lag.. time it takes turbo to start making boost or time it takes from 0psi.. to what ever boost you wanna run? etc..

sydney kid, i have a rb20 silvia. has some stupid diff gears.. 3800, 110 in fth.. or 3500 at 100 in 5th.. lets say i get all the suppport systems, fuel, ecu, fmic etc.. then put a hks 3037 on it.. would a car with the EXACT same mods but a 2835 or similar but with less lag therefore lower power.. beat me weather it be on a highway or drag strip or in roys case... track?

[b0neR]

yeah i was wondering that...

[rbs13]

roy.. you need to go into the corner faster.. higher speed. slap it into 3rd.. bring the tail out.. keep ya foot down.... if ya get my drift

[Roy]

lol...not a good idea encouraging me, im enough of a liability trying to keep the thing off the walls without trying to punt the car sideways.

It comes down to so many factors, especially when considering the power levels your looking at in a car as light as yours...suspension, tyres, diff, A/R of turbos your looking at.

[Sydneykid]

Hi rbs13, your 110 kph @ 3800 rpm = 28 kph per 1,000 rpm, that's pretty normal Silvia gearing.

The diff ratio is irrelevant anyway, change the diff ratio and you don't change the rpm drop on upchanges. You have to change the gearbox ratios to affect that.

As for the 3037 versus 2835 comparison. Whatever car has the highest average power will accelerate faster thought the gears. The single maximum power at one rpm point is irrelevant.

That's why, for example, a drag GTR with a pair of 3037's will need a close ratio gearbox to use the narrow power band of that size of turbo. Lessen the amount of rpm drop so increases the average power. That's why a car with a close ratio gearbox will be faster than the exactly the same car (and engine) with a standard ratio gearbox.

Hope that explains further

[rbs13]

none of my friends sit that high in their cars at all most sit at in their s13s with std diff, etc 3200.. so im guessing i have 4.3's? so would that give me a top speed of round 230-240kph? just that one of my friends has a 200sx.. max power is 327rwkw at 1.35 bar.. im not sure what turbo it is.. but its big! also that power is at 7400.. the car is damn laggy.. even appears so on the highway racing other cars (dont condone just using example) say i come up to him and drop to 3rd.. making me sit at eg.. 5000.. he mite be sitting a bit lower in 3rd. cause i have different ratio's. at 5000rpm with what ever turbo i choose to use i would be WAY better off than him i would think therefore probably beating him for a while.. but i still think he has the power to catch up and possible pass me.. is it true 1 second on the strip = 1 car length.. meaning he would have to run 12's to catch up to my 13 second car if i got a lead of 1 car length or he was at my rear wheel.. or so. lets say he has a 3040 starts boosting 4000.. max boost 5200-5500.. and i have a 3020 (example) thats starts boosting 3500 but has full boost by 4600-4800 both running 1.5 bar.. we both gun it... would he have enough power to beat me if his car has a max of 340rwkw at 7500 and mine is 290rwkw at 8000k

sorry if its a jumbled up post just have a couple of questions regarding this...

[Roy]

It takes a substantial power advantage to ovetake someone once they have a lead/break. Well thats my experience anyway.

Like Sydneykid explained, if your setup is too peaky then this problem occurs every gear change.

[Sydneykid]

Sorry rbs13 I can't answer that question, not enough data. The only way to do is to map out the power from a dyno chart at the rpm's you are talking about.

As for time and speed, 160 kph (100 mph) at the end of the 1/4, is 44 metres per second. A Silvia is (conveniently) around 4.4 metres long, so 1/10th = 1 car length.

Hope that answers that question

[rbs13]

Meanwhile the other car had;

170 rwkw (when you were at 93). That's a 77 rwkw advantage

200 rwkw (when you were at 195). That's a 5 rwkw advantage

240 rwkw (when you were at 250). That's a 5 rwkw disadvantage

260 rwkw (when you were at 300). That's a 40 rwkw disadvantage

what turbo would do that(170-200-240-260) if it is at all possible on a rb20?

[b0neR]

2540?

[rbs13]

i would of thought a 2540 would be too small for that lets make it boost is limited to 1.4bar..

[Roy]

I think you will find you would require a modified RB20 to make those figures. At a minimum some cams and light head work.

[rbs13]

fmic, exhaust, ecu, injectors, pump, fuel reg, possibly cams, possibly porting, ebc will be done.. turbo is only thing undecided..not limited to internal gate either.. bottom end will remain untouched.. as it is only a rb20.. if i wanted BIG numbers i think a rb26 would be slotted in.. or would it just be easier to slot in a rb26 in the first place? exhuast, boost up would have the rb26 pushing a silvia pretty hard.. but would it be worth the expence for just a silvia.. probably not