Just been out in an N/A..

Hey guys,

 

A few of you might remember when I popped off my i/c piping and temporarily lost my turbo's, I made a comment about how that must be what it was like to have an N/A. I was quickly corrected and told that my TT would be running crap at that point and that an N/A was mapped differently etc, and would be entirely different.

 

Trig has just taken me out in his, and I have to say that I am very impressed, it's by no means a slouch! A quick car, and a very worthy Supra even without the TT

 

I hope you enjoy your purchase mate

Yay, at last!! A compliment about N/A's!! Many thanks m8, it's about time!

LOL cheers fella. Didnt mean to scare you tho

Am loving the leather so much Looks and feels so much better now PS you owe me a ride in yours now too

Fark no its no slouch, I've said this before but some people just don't know how to get off their high horse. Most TT owners will forever be ignorant just because they can be.

 

N/A power for life!

LOL cheers fella. Didnt mean to scare you tho

Hehe, you have a slightly more aggressive driving style than me

 

Am loving the leather so much Looks and feels so much better now

Glad your happy mate. How was the drive home in the thunder and lighting? Comfy i'd say!

 

PS you owe me a ride in yours now too

How's your october? Mine's terrible, we'll talk in november

Reading Toyota's blurb, the n/a mkiv has a quite sophisticated induction system. 220bhp out of a 3lt ain't too bad, especially with the nice, fat torque curve it's got.

Ohhh Trig what u had done to the car now !!! ....

Reading Toyota's blurb, the n/a mkiv has a quite sophisticated induction system. 220bhp out of a 3lt ain't too bad, especially with the nice, fat torque curve it's got.

Its a two-mode tuned plenum. Probably close to state of the art when the engine was designed.

 

If anyone wants a project, I'd be insterested to see what a really long link pipe from one half of the plenum to the other would do for low-down torque.

 

Its a two-mode tuned plenum. Probably close to state of the art when the engine was designed.

 

If anyone wants a project, I'd be insterested to see what a really long link pipe from one half of the plenum to the other would do for low-down torque.

 

 

Digsy, with-out getting too techy, can you explain what sort of result you would expect to see with that sort of mod and how its achieved, still learning here

Its to do with the resnonant frequensies in the plenum.

 

The NA plenum is divided into two parts, one for cylinders 1, 2 and 3, and the other for cylinders 4, 5 and 6. There is a valve between the two which can be either open or closed.

 

If you look at an NA engine, after the main throttle the intake pipe splits into two well before the plenum. Thie means that any air moving from one half of the plenum to the other has to travel a long path, so any resonant tuning will have low frequency and so benefit torque at low engine speeds.

 

If the link valve is open, however, this effect is destroyed and the resonant frequencies move higher, and benefit airflow at high engine speeds and top end power.

 

If you ran two dyno curves back to back, one with the link valve open and one with the link valve closed you should get two torque curves which cross over. The proper point in the rev range to open the valve is where the two curves cross, so you effectuvely get the better half of both curves.

 

What you could do is add another link pipe between the far ends of the plenum which was even longer than the long link mentioned above, and control that with a third valve. Theoretically it would give you even more low-down torque.

 

Three-mode plenums are quite common on V6 engines.

Interesting, how homogenous is this theory with going na-t, my thoughts run like this :-

 

When going na-t for big power you must do something to lower the compression, which in turn lowers the low down torque, If you could employ your theory for the long link pipe you should be able to regain some of the torque back, bearing in mind (I think) that you haven't increased the compression with this mod only altered the flow.

 

Does this thinking make any sense or am I talking rubbish?

Three-mode plenums are quite common on V6 engines.

My old MX6 being a case in point. The JSpec engine produced 198 bhp from a 2.5L V6 and used 2 valves in the plenum to change the length at 3 set points.

I dont think TT drivers think they are on high horses compared to the NA, well I don't hold anything against the NA. What attracted me to the car - its looks, I decided on a TT as tuning potential is better bang for buck, plus I wanted a six speed box (sad that little things like a six speed box would make me choose it!).

Although I now know that they do a 6 sd in the NA the SZ-R - correct me if I'm wrong.

Ohhh Trig what u had done to the car now !!! ....

 

LOL dont worry mate, will be posted up in a thread soon nothing major tho

Hehe, you have a slightly more aggressive driving style than me

 

Glad your happy mate. How was the drive home in the thunder and lighting? Comfy i'd say!

 

How's your october? Mine's terrible, we'll talk in november

 

LOL! aggresive is a good word

 

The drive home was a nightmare. at times i couldnt even see 10ft in front of me! The M1 was shut down to one lane as there was a bad accident, then 3 more were up the road. Almost aqua-planed into the central reservation as well luckily i didnt

 

November is good mate, whenever youre ready If you need a lift to JAE let me know

Interesting, how homogenous is this theory with going na-t, my thoughts run like this :-

 

When going na-t for big power you must do something to lower the compression, which in turn lowers the low down torque, If you could employ your theory for the long link pipe you should be able to regain some of the torque back, bearing in mind (I think) that you haven't increased the compression with this mod only altered the flow.

 

Does this thinking make any sense or am I talking rubbish?

When off-boost, yes, it should work. On boost it doesn't matter.

 

Incidentally, tuning the length and diameter of the link pipe is no simple matter

If you need a lift to JAE let me know

If you could that would be awesome mate, was considering giving it a miss. My other Jap 'Beast' doesn't really do it for me, lol!

 

Almost aqua-planed into the central reservation as well

Did you 'aggressively' correct it?

When off-boost, yes, it should work. On boost it doesn't matter.

 

Sorry, should of explained myself better, I meant when off boost.

 

When discussing the pro's and con's between the TT and the NA at meets or on here it always comes up that the NA is quicker off the mark than the TT due to the TT having to sacrifice compression, and therefore torque, for its turbo's (obviously it soon blasts past when it gets on boost).

 

This is also a sacrifice that anybody considering going na-t for big power will have to make, but due to the nature of the na's intake system what your theory suggests is it would seem possible to gain some of this low down torque back (I'm guessing that you probably won't get it all back),

 

So the best of both worlds, Quicker off the mark than a standard TT plus the benefit of a turbo (and we haven't discussed the difference in the gearing between the two cars yet).

 

Why can't this theory work on the TT (or big single), is it purely down to the components in the TT intake system?

 

Incidentally, tuning the length and diameter of the link pipe is no simple matter

 

Yeah, I'm guessing there would need to be alot of flowbench work done.

 

EDIT: Or "trial and error"

Reading Toyota's blurb, the n/a mkiv has a quite sophisticated induction system. 220bhp out of a 3lt ain't too bad, especially with the nice, fat torque curve it's got.

 

The S2000 is 240bhp from NA 2l, and a lot lighter

 

(just to bring you N/A owners down a peg or two on a big up NA thread )

 

The S2000 is 240bhp from NA 2l, and a lot lighter

 

(just to bring you N/A owners down a peg or two on a big up NA thread )

 

 

 

Yeah, but its a Honda!!

the S2000 has very average torque. I think 150 ftlb when the NA supra has 210 ftlb

Yeah, the Honda gets its big power from modest torque by revving its nuts off. Its also about 7 years younger than the Supra and much more complex and advanced.

 

MInd you, 120hp / litre isn't to be sneezed at in any way, shape or form.

 

 

As for TTs being slower off the line, I can't say I've realy noticed it. They always seem to outpace me pretty smartly from the off. Turbo number one comes on song pretty fast, doesn't it?

LOL! Thought that would get you going!

 

May have only about 150lb/ft, still doesn't stop it doing the 0-60 rush in 5.5 seconds

The S2000 is 240bhp from NA 2l, and a lot lighter

That's always the problem with people sticking to just a 'bhp' and 'torque' figures.

These are maximums, and don't say much on their own.

You need to look at the curves, and see how early they make most of their torque and for how long (in revs) they can sustain that figure.

 

You could get lots of 'bhp' by making unimpressive amounts of torque (but at very high revs). That's what the S2000 does.

You could also get lots of 'bhp' by making impressive amounts of torque at very LOW revs (fitting a V8 for example)

Guess which one is nicer to drive, especially if it's a heavy car.