I have an 07 427r roush that has had substantial mods. for now I'll only list the mods to the engine as that's the only thing I'm having problems with. we built the engine to a 298 ci stroker with livernois stage 2 heads, all forged internals, roush tvs blower running about 16 lbs boost, 52 lb injectors, twin gt500 fuel pumps, comp cams stage 2 blower grind with cam timing locked in full advanced, and inch and three quarter headers. the car put 618 hp and 608 tq to the wheels, so I'm happy with the power, but it has driveability issues that I need help with. the shop that did the work for me has tried tunes with diablo, sct, and hp tuners and still can't get it right. it seems to do best on hp tuners. the main problem is hunting for idle when I push the clutch in and come to a stop, or if I'm just sitting idling and rev the motor it will make it hunt (surge) for 3 or 4 times and then will idle nicely. this makes it hard to take off smoothly too because of the engine surging when I try to give it a little gas to take off. the other thing it's doing is when I shift gears the rpm's sometimes (depending on how hard I take off) do not want to fall back as quickly as they should. that makes it hard to shift smoothly because I never know when the rpm's will fall right and when they won't. the tuner at the shop says it is just hard to get everything just right on a car this modified with the big cams. do you have any ideas?

We are currently out of town in Orlando FL for the Performance Racing Industry Tradeshow. I will have Aric respond to your questions when we return next week. We look forward to working with you.

With out looking at the vehicle it sounds like to much air is added to the dashpot, continuing to bleed off when it should be idling or depending how much overlap the cams have.... the by-pass valve on the blower maybe moving around causing some issues. I can be a few other things, too.

here are the cam specs if they help you any, just wondering if you think this combination is tunable to where we can get all my issues remedied?
gross valve lift-.547intake .560exhaust
cam lobe lift-.2670intake .2750exhaust
adv. dur. @.006 valve lift- 272intake 287exhaust
valve timing @.050 intake open 16btdc, close 40 abdc
exhaust open 68bbdc, close 0 atdc
intake center line 102.0, exhaust center line 124.0 installed
duration @.050 intake 237, exhaust 248

Honestly, without seeing the car and gathering some data from it. Its very hard to say I can fix it with tuning. A Lot of times it is a hardware problem that will get mistaken as a software (tuning) problem. Give Ryan a call and lets take a look at whats going on.

This post was last modified: 12-19-2009 11:23 AM by RYAN@INJECTED.

ok thanks for the info. since we started talking my tuner has adjusted the tune again and the weather hasn't let me drive the car enough to see how it will do for sure, so far it does seem a bit better but I'll let you know. It may be a month or so, because I don't drive it much in winter and with holidays coming I don't have time to schedule anything now, bare with me and if I still have issues I will call you. thanks again, Luther.

No problem Luther. Enjoy the holidays.