Thats the one!!
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But that is exactly what you want with an auto.
An auto has a thing called a TORQUE convertor. What this thing does is multiplies the torque of the motor. Therefore an auto produces huge amounts of torque down low. Since you have more than you need in the lower rev ranges, you are better off trying to raise the torque/power curve up in the rev range a little. Cams and other mods that produce low down torque are a waste in the auto and tend to take the performance away from the 2,000 to 3,000 rev range where it is really useful.
Pretty much that, wlthough I'd can the extractors, the efi manifolds are good enough and the $ for HP ain't worth it, plus free flowing exhausts decrease torque
Next step, is working on ignition timing and aomething to control fuelling better, but you starting to add $$, so more imprtantly, what's the budget?
Im watching this with a lot of interest.I am thinking of doing the same thing except with a 3.5 V8 and auto.Sorry to hijack your thread but is it easy enough to change the cam with just the heads off?If you think your 3.9 is gutless come for a ride in mine:eek: Took Stirling out in mine last night after we put the new dizzy in and he says" Is that flat to the floor?". And my reply is "Yup it sure is".:Rolling::Rolling: I would be looking at a cam which brings the torque down lower in mine and maybe a little port work because the Rover heads are pretty bad.
Dynotec PC216 cam, some port MATCHING both exhaust and inlet, some EFI manifolds and a compression lift, head skimming and steel head gaskets. Don't machine too much due to the mismatch of inlet manifold angles and the need for rocker pedastal shims etc. PhillipA has some info about what heads/ chambers produce better comp ratios too, I can't rmember them of the top of my head.(Pardon the pun)
The biggest help would also be a remapped ECU. The difference with decent fuelling to these hotwire EFI engines is huge, and you can then run more advance etc...:twisted: All of this without significant fuel consumption issues, even less if you don't push the loud pedal TOO much:twisted: (As IF!)
JC
The biggest improvements are to be found in the heads, depending on your budget. TRS have the RPI big valve ported heads for about 2 grand or you can fit a pair of cast iron Buick 300 heads, enormous ports and instant bolt on power. There are a pair on the 'bay at the moment for about a $150 bucks, combined with a cam, mapping, exhaust, figures of 30-50 more hp are not unreasonable expectations. any more than that and be prepared to mortgage the house.
You dont need to take the heads off to change a cam. however radiator, A/C condenser, timing cover, dizzy, intake manifold, sump etc all need to be removed as the cam comes thru the front. Do your timing chain and gears while you're there. DONT FORGET TO DO YOUR LIFTERS AND ONLY USE ONES LISTED FOR YOUR ENGINE, not Holden or Chev V8!!! Others here will tell you otherwise, but if you dont want to do it again.........
A point of note on the 3.5 intake ports, size wise they are likened to a fishes freckle at 20,000 leagues under the sea!! Someone correct me if I am wrong but a good set of 3.9 heads and manifold will make a difference on their own, much as justinc pointed out
Sounds like fun doesnt it!! ;)