MicroSquirt.com read only forum (Jan.15,2018)

Hi, anyone got any experience of running a large port 4AGE with the TVIS plate removed (or butterflys permanently open) ?

It shouldn't be hard to tune around it , but wondering if it would be better to shorten the manifold a little so the TVIS can be left in.

(Mini install so fairly tight engine bay)

tvis when in working condition and activated correctly will always provide an increase in down low torque.
the ports are just too big on the bluetop 4age.

you can remove it, and it will be fine, but you will lose the ability to generate this extra torque.
Make sure you remove the locators in the head, or else you will torque the manifold up and break it.
You'll probably need to remove the studs and get some shorter bolts.

itb's on a bluetop don't run as good as itb's on a smallport (redtop) because of port size I believe.

I've already removed it as part of the 'speed build' but was wondering if I'll really need it in the long run.

I pulled out the locator rings, and just added some spacers to the bolts so it's easily reversible.

http://www.spagweb.com/gallery/ed_06_mr_ed

I guess I just need to drive it to see

After 100 miles of gentle pottering (honest) I really haven't found there to be a big black hole in the low torque without the TVIS stuffs, so will probably run as is for a while longer.

Hopefully get things mapped properly in the next few days using the LC-1, so will see when it's driven a bit harder...

As Karl said above.. the main reason for TVIS is the lower end torque. If you've done some "gentle pottering" as you said previously, you probably would not notice any difference one way or the other. It's the high throttle low rpm where the difference would be noticed (especially on a dyno).

Are you naturally aspirated or forced induction?

If you're NA, I would suggest leaving the TVIS system in tact and looking into having MS trigger it using the outputs section of MSnS-Extra (with appropriate board modifications).

If you are boosted, you could set the outputs as NA would have them configured but then possibly have a boost trigger (such as using the nitrous turbo spool output) to have them open whenever you are under boost to give you the gains throughout the powerband where the TVIS values are no longer accurate.

Hi,

The 'gentle pottering' was maybe a bit of a lie - hence the (honest)

After a bit more serious mapping, it seems to drive really well, and pull happily from 1500 rpm. Perhaps having 200kg less car to drag around helps a bit with that one !!!

If I can find someone local (& cheap) who can tig the inlet back together, then I will chop an inch out of it so there's room for the TVIS plate to go back in. At present - without the TVIS there's only about 10mm between the inlet manifold and master cyls !!!



However, I did pick up a cheap DCOE manifold, and do still have the CBR929 throttle bodies that were going on the V8, so could nick 4 for this.....

cool, run the itb's... sucks to standard manifold!