hi guys
Marks pump already has the full governor removal mod
when i did his pump it had all the good stuff done
100 % fuel increase over stock with no increase to the no
boost setting.
almost 20 deg pump timing advance
the limitation to the fueling is due to the rotary camplate inside the
pump.
at speeds above 5000 the rollers on the cam start to skip and you
don't get the full pump lift anymore. i have increased the tension
on the internal springs but with the current parts we're using i can't
upgrade to the Cummins return springs.
i can only use the Cummins springs if we upgrade the Head, cam plate
drive shaft and a few other pieces too.
i can only geuss the price of all those parts. maybe $1500
Giles
Thanks for the info Giles
this is a little more detailed than I gathered from 935racer's phone conversation with you.
I want to say that your pump seriously kicks ass, it's a major contributor to this TD's performance. Basic pump DIY stuff doesn't cut it. Now that 935racer managed to make this car virtually smoke-free with his head work, I have to get back to you for more fueling solutions!
It's like the story of a general developing a superior tank during World War II - he takes the tank to a armour builder and tells them to develop an armour that will resist a shell. He then takes it to an armourer and tells them to make new shells that will pierce this armour. Then he goes back to the amour builder again for an armour upgrade and so on.
Giles, would it be possible to get
custom TD style return springs with tension that is comparible to the Cummins springs you mentioned? Accompanied with a mild 10mm or 11mm pump head upgrade it might do the job without needing to spend excessively on other Cummins parts. I need to rev higher. I didn't buy heavy duty valve springs for nothing!
How did the TD drag vehicles that rev up to 7,000 RPM do it?
By logic I'm not sure how Cummins return springs would help me rev higher. Cummins have very low rev and although their springs are stiffer, throwing in a high lift camplate
might negate my chance to rev well past 5,000 RPM. A 12mm head also seems to have reliability issues after the 5,000RPM point. I've seen a few explode.. including a friend's whose I sent a 12mm head to.
Regardless, have you by any chance built a TD pump like this and found good results past 5k RPM? Say up to 6,500 or even 7,000 RPM? I understand if you haven't because this is an extreme TD example, 1.6L even.
Your contribution to TD performance is greatly appreciated.
If, ultimately, revving past 5,000 RPM with 10mm or 11mm head and custom TD springs is not feasible, then I will consider going the Cummins route and keep my powerband below 5,000 RPM if required to maintain pump reliability. Could have lots more torque to get a fair increase in HP. This would further necessitate a compound turbo setup.
Cheers,