Poor Topspeed with KLZE

[12get]

Hi,

The title tells it all.

The car has a KLZE with KF transmission.
Acceleration is nice, nothing to complain about.
But Top speed is way too low:
Running 205km/h @7200 rpm, 225km/h @ 6500 rpm. (I was able to reach same speeds with my old K8 setup) .

It reaches these speeds without problems, but then it seems as it would not have enough power to continue.
Even if I would continue 10 km with full throttle, it is unable to get higher rpms.
In third gear, I can easily hit the limiter @ 7500rpm.
I don't think that the KF transmission is too long, because if so, I would expect it to reach higher spped in 4th gear than in 5th gear.

Exhaust system is: XS Headers, matal cat, and 2.5" free flow exhaust System.
The change from stock exhaust system to the new one made no difference in topspeed, acceleration was imnproved.

Distributer is new.
Tried with KL31 and KL36 ECU, tried different spark plug leads, tried new air flow meter, tried fuel pressure regulator, nothing made a difference.

Any ideas what could solve my problem?

[ninjajim4]

do you know what a speed limiter is..?

[12get]

Both tested ECU should not have a speed limiter.
As far as I know, several guys use the same ECU types here in Germany and can run higher speeds.
Or did you mean the rev limiter? -The rev limiter should come at 7500rpm, so it cannot be the limiting factor.

[Ryan]

The different transmission might be causing you the issue. Have you tried a Ford Probe GT (or your equivalent in Germany) transmission? Or a Mazda 626?

[ninjajim4]

not true. there IS a speed limiter:

http://ww.mx-3.com/phpBB3/viewtopic.php ... &view=next" onclick="window.open(this.href);return false;

[Ryan]

Thanks, ninjajim4, (Jim, is it?), I didn't know that I always thought we had just the fuel cut at 7.5ish, and then power top limit.

Yay for learning something new.

[12get]

Oh, really? If that's true it would be nearly too simple.
I didn't the engine swap on my own, but the one who did, did it already several times and I would definately say, that he knows what to do.
I also asked him, if it could be that there is a speed limiter, but he was sure that there is no active speed limiter.
I'll have a look at the cables later, maybe he already cut the line of the speed limiter.

Well, this is the first time he built a KLZE in combination with a KF transmission, maybe this is causing something special?

How would the speed limiter act, if active? Like the rev limiter, that you feel a fuel cut or is it more soft.
Because when I hit 205km/h in 4th, or 225 in 5th, it does not feel like a fuel cut, it is very soft, just not going to higher rpms, definately no fuel cut like I know from the the rev limiter.

[12get]

Allright, just back from track. speed limiter removed, no difference.
Used my GPS amd it's really bad. In 4th gear 195@7200rpm, 5th gear 211@6400rpm, maybe I could have pushed it 100rpm higher, but then not any further.

The transmission seems not to be the problem, as I phoned the guy today, who did the swap and he told me that in the meantime, he did a second swap with the KF transmission and that mx-3 easily hits 240.

Vris is working as it should, I have no idea where the power is...
He also has no idea, only further step I could think of would be to raise the fuel pressure.
And to be honest, I think it will make it a bit better, but will not be the real problem.

[ninjajim4]

not sure what to say, but i did neglect to mention i thought it was strange bc even at 225 kph, you're already above what the limiter is supposed to restrict you to...

[12get]

Well, the reason why it did not work is simple. When the engines are imported to europe, the guy who imports them already removes the speed limiter in the ecu.
As I said, it would have been too simple.
But thank you for your advice, because I already spent so much money on the swap, and from firat engine start, the problem exists. So I am thankfull for every imformation about this. Now I can exclude, that there is aspeed limiter. Before I was not sure.

[_-Night-Shade-_]

What size tires are you running?

[12get]

215/40 on Motec Nitro 9x17, 8.5kg weight. Should also be no problem. Drove them already on the K8, without experiencing low or even no loss of topspeed.

[hgallegos915]

I dont think it matters what engine you have, the transmission tops at what the transmission tops. My probe transmission tops at 140 (im sure it may be off and its less) and I have a klze turbo.

Why do you want top speed tho? It can get you some serious jail time?(in the us at least)

Its not how fast it can reach but how fast it can get there imo.

[12get]

In Germany we have the Autobahn, you forgot? So jail can wait.
But just to explain:
I am not hunting the ultimative topspeed. I am just making topspeed test, because for me, it is the best indicator to see if the performance is right.
If I would just use accelleration for testing, I definately would be most of the times wrong,because it is a feelig that can easily fools you.
One day you think it performs top, the other it is weak. Both days the true performance was the same and you felt only a difference because of your mood.
A dyno would be best, to check whats the performance, but it also works to check if there is any improvement in topspeed after you made some changes.

As I wrote above, I don't think it is the transmission, because same setup on another mx-3 reaches 240 easily with the kf.

[RX8SE3P]

You'd have to run a dyno test. Top speed is a very interesting thing. At over 6500rpms the KLZE is losing power, when you have all that wind resistance also, it is not easy to gain speed.

People hitting 240 might be going downhill or with the wind at their back. Also the transmission would affect the speed. You are almost maxing out the gears and the revs are too high to be making much power. 225 sounds about right, the K8 will almost have the same top speed but how fast it can get there is another story.

I find on highways that fast revvy engines and even small turbo engines don't do as easily as V8's and big V6's do when it comes to high speed overtaking. The bigger engines have the torque from lower in the rev range and usually have gearboxes to suit it. They won't win 1/4 mile against our KLZE's but they will hold up very well on the highway like the Autobahn.

The MX6 gearbox has the longest of gears, longer than the K8 but not sure about the KF, I believe the KF and K8 gearbox are the same. For more highway driving I would recommend the MX6 gearbox.