Forged Performance: Project 370Z Race Car Build!!

Sharif@Forged · 08-10-2009, 02:15 PM

Quote:

Originally Posted by t-ray

Sorry, my question was not one of reliability, rather it was in regards to the final drive ratio. How often do you top out 5th gear? And if you ever do, can you actually accelerate in 6th gear at those speeds?

You will definately use 6th gear at many tracks, and there is acceleration capability in 6th in problem at all.

Really depends on the track, as to how often you will use 6th gear.

Does that answer your question?

t-ray · 08-10-2009, 04:37 PM

Yes, thanks. I know it's probably a newb question, but I've never taken anything over ~120mph.

At your target hp levels, at that weight, that car is going to be major fun. But I bet if would be even moreso with 3.9's or 4.0's in there.

Sharif@Forged · 08-11-2009, 06:48 PM

Quote:

Originally Posted by t-ray

Yes, thanks. I know it's probably a newb question, but I've never taken anything over ~120mph.

At our levels, at that weight, that car is going to be major fun. But I bet if would be even moreso with 3.9's or 4.0's in there.

3.9 would be too short a gear for the power levels, and intended use for this car.

For an NA car, and more moderate power/weight setup, there may be some benifit to the 3.9 rear end.

t-ray · 08-12-2009, 10:50 AM

Quote:

Originally Posted by Sharif@Forged

3.9 would be too short a gear for the power levels, and intended use for this car.

For an NA car, and more moderate power/weight setup, there may be some benifit to the 3.9 rear end.

God I can be such a dumb **** sometimes. I meant "your" power levels, and I totally forgot that you were going to be adding boost at some point in the future. I was framing the gears question in terms of the car staying NA.

Sorry for the confusion.

So - going back to one of my earlier questions, NA, where does the car stop accelerating?

wstar · 08-12-2009, 11:05 AM

Quote:

Originally Posted by t-ray

God I can be such a dumb **** sometimes. I meant "your" power levels, and I totally forgot that you were going to be adding boost at some point in the future. I was framing the gears question in terms of the car staying NA.

Sorry for the confusion.

So - going back to one of my earlier questions, NA, where does the car stop accelerating?

Well the answer to that is "at the drag limit", and I don't think many people know that since the ECU speed limiter is below the drag limit. If I had to guess, I'd say with no wind it's probably around 170-180 mph with good bolt-ons in top gear, although it probably varies by transmission type. You'd probably loose all steering control and wreck the car before then though, at least without some aero upgrades and/or lowering to keep the nose planted harder.

wstar · 08-12-2009, 11:09 AM

A more useful answer: I don't think I would see myself using my 7AT's 6th or 7th gear to accelerate on any reasonable track. If the track had a long slow curve or straight where for whatever unrelated reasons I desired to maintain constant speed for a stretch, I might drop into 6 or 7 just to give the engine a rest, but useful acceleration at speeds the stock aerodynamics can handle all occur in gears 1-5 on the 7AT w/ stock diff ratio. 6MT may have a different answer, as the transmission and diff ratios are all different.

t-ray · 08-12-2009, 01:33 PM

Quote:

Originally Posted by wstar

A more useful answer: I don't think I would see myself using my 7AT's 6th or 7th gear to accelerate on any reasonable track. If the track had a long slow curve or straight where for whatever unrelated reasons I desired to maintain constant speed for a stretch, I might drop into 6 or 7 just to give the engine a rest, but useful acceleration at speeds the stock aerodynamics can handle all occur in gears 1-5 on the 7AT w/ stock diff ratio. 6MT may have a different answer, as the transmission and diff ratios are all different.

That is ultimately where I was going with the gears question - based on the assumption that the car remained NA. I was wondering a gearing-reduced top speed had any practical impacts on real-world tracks.

08-12-2009, 11:09 AM	#6 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3596	A more useful answer: I don't think I would see myself using my 7AT's 6th or 7th gear to accelerate on any reasonable track. If the track had a long slow curve or straight where for whatever unrelated reasons I desired to maintain constant speed for a stretch, I might drop into 6 or 7 just to give the engine a rest, but useful acceleration at speeds the stock aerodynamics can handle all occur in gears 1-5 on the 7AT w/ stock diff ratio. 6MT may have a different answer, as the transmission and diff ratios are all different. __________________ 7AT Track Car! Journal thread / Car setup details

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08-10-2009, 04:37 PM	#2 (permalink)
t-ray Base Member Join Date: Apr 2009 Location: bham al Posts: 91 Drives: 05 g sedan 6mt Rep Power: 18	Yes, thanks. I know it's probably a newb question, but I've never taken anything over ~120mph. At your target hp levels, at that weight, that car is going to be major fun. But I bet if would be even moreso with 3.9's or 4.0's in there.