Rev limit raised to 9710

[Brett928S2]

Hi All

Just paid John Speake (928 Electronics Guru - http://www.jdsporsche.com/) for a LH chip which will remove my 6375 rev limit and raise it to 9710.

The reason I am doing this is that when I go for my 200 mph plus runs I do NOT want the car to hit the rev limiter as on a 928 that leans out the fuel and when running huge quantities of Nitrous , a lean engine would equal a HUGE bang []

When my 1000 HP system is fitted I will be running an extra 8 Venom fuel injectors (1 for each plenum leg) so extra fuel = good , not enough fuel = bad....lol []

All the best Brett

 

[Geoff_Fields]

What maximum revs do you intend to use Brett? I would have thought 9710rpm would also result in a big bang!

 

[John Sims]

Granted I know nothing but I would have thought the engine is going to find its own limit way before 9.7k.

It has taken some pretty high level technology, and expensive metals to get engines up around 9K (assuming you want to run them again without a rebuild). The 928 has some pretty big pistons and not the most high tech of internals. I would have thought hanging on to those monster buckets at 9K would be next to impossible.

 

[Mark_Bennett]

Oh I don't know. The old FIAT 128 engine series had a 5 bearing crank and was well balanced at the factory. I regularly saw 8000 RPM in my old X1/9 around corners on tracks, and it went on for well over 100,000 miles. Granted the engine was only 1/3 the size of the 928...[]

 

[John Sims]

Most hire cars rev to 9K quite readily in my experience so technology has moved on a pace. []

I still think if Porsche set a rev limit just over 6K to go half as much again has to be pushing the envelope.

 

[Brett928S2]

ORIGINAL: Geoff997

What maximum revs do you intend to use Brett? I would have thought 9710rpm would also result in a big bang!

Hi Geoff

You are correct lol....9000 would be a big bang

I should hit a maximum of 7000 for my run ...the main point was MOVING the rev limit away from 6375....if I hit that limit running 1000 hp of Nitrous I would be picking bits of my engine up for months

All the best Brett

 

[Hilux]

Hi Brett

I must admit I`m fascinated with your ongoing project so keep us posted however in your upgrades you dont mention brakes? Its a lot of power without an upgrade and a parachute is only part of the equation?

 

[Brett928S2]

ORIGINAL: Hilux

Hi Brett

I must admit I`m fascinated with your ongoing project so keep us posted however in your upgrades you dont mention brakes? Its a lot of power without an upgrade and a parachute is only part of the equation?

Hi Paul

Thanks for the interest

Brakes are 4 pot Brembos all round and a chute will cut speed by 50% in less than a second lol, its one of the reasons why I also have fitted the full race seat and 6 point harnesses.because I figure I would like to stay on MY side of the windscreen when I hit the chute lever lol....

Chutes are amazingly good and having used them in the past, I consider it worthwhile....I am a "belt and braces" man so IF I get this badly wrong ,it will be nice to be able to pull that chute if needed in an emergency

The 9710 rev limit chip has arrived and I will fit and test this week (my neighbours are going to love that lol)

All the best Brett

 

[Alex Postan]

Brett, do please give us some advance warning so that we can all be there. Heroic triumph or gloroius failure are equally godlike[8D]
Bring it On!

 

[Brett928S2]

Hi All

Just fitted the new LH chip from John Speake (thanks John) which has the 9710 limit...

Took the revs up slowly 1000 revs at a time until 6375 (where limit was previously) then in 200 rev chunks until I hit 7200 ,where I could just about hear the valves starting to float and held it there for around 10 seconds then shut it down and all fine

I "think" it would probably run at higher revs than 7200 for a "short period" but wont risk it until my actual 200 mph plus runs.....lol

I dont think I will need to anyway as 7200 equates to around 235 mph [][8D][]

But you never know.........

All the best Brett