Contour Enthusiasts Group Archives Forums Modifications Forced Induction S/C for Regular DURATEC to Perform at SVT standards???

The Vortec kit for the regular duratec lacked 50hp from the SVT one. If I stuck the SVT intake manifolds (upper and lower), 65 or 75mm throttle body, larger custom exaust, SVT cams...that's probably only about 20-25hp... that's basic what else (besides re-boaring for new pistons) would someone have to do to achieve this?? I saw someone hitting 285 wheel HP (SVT), what the heck did he do to achieve so much more than expected??? IDEAS?????

The Vortech claims are based off of adding their S/C to a stock car.

The SVT with it's much better breathing (and cams & CR & etc) magnifies it's mods & the S/C much more than a Non-SVT engine would.

One thing you forgot in your list is the higher compression of the SVT vs. regular duratec. This I beleive adds a fair amount to the mix as the air is all ready more compressed. Someone please correct me if I'm wrong.

Rick

Starting with a lower CR on the stoc 2.5 should allow you more boost than the SVT.The extra cam overlap does not help s/c or t/c,in fact you want less to stop the 'blow out' at boost pressures,s/c-t/c motors do not need the hot grinds.

Only problem with that, Terry, is the limitations to the Vortech drive system. In order to run more boost that drive shaft has to be spun quite a bit faster with the use of a much smaller pulley... we have seen (And discussed at great length :D) what the stock drive system does with the stock pulley so going smaller to get more in this case can be more damaging to the engine & forced induction system in this case then if it were a turbo.
-Mark

I think you will find that the max boost is limited by the blow off valve ,not the pulley so an upped blow off would give you the higher boost without doing anything to the pulley at top end.

Well the stock Vortech bypass opens at 10psi. At WOT on the dyno in 4th gear you are only pulling approx 7-7.5psi when the rev limiter kits. I guess I don't see how going to a higher psi setting on a new bypass would change that without increasing the impeller rpm's.
What am I overlooking?
-Mark

So at whatt speed/gear DO you get to 10psi to open the by-pass?

7500rpms in 1st usually puts me between 9.5-10psi
7500rpms in 2nd usually puts me at 8-9psi
7500rpms in 3 & 4 are about 7.5 on average.
and in fifth approaching redline I haven't seen more then 6.5psi.

During WOT the bypass only seems to open during shift points & when the car hits the rev limiter. During regular driving the bypass is almost always open and the car remains in vacuum.

-Mark

Confused? How can the by-pass be open(max boost) and the manifold be at neg atmos???...

The bypass doesn't have a spring to keep it closed, it uses intake pressure to close the bypass. So if the intake pressure isn't great enough it stays open.

Its just a closed loop non-adjustable Bosch Bypass valve.

-Mark

I still dont see how in normal driving you get no boost???,what about engine speeds below 7500??,sounds like it is not progressive at all,should have a transition across the rev range from vac to pressure ,not a sudden '0-7psi ...bang!'

It's not 0-7psi instantly.

Prime example is high way speeds, if you are cruising 70mph a little over 3 grand the car is pulling 15" of vacuum, the moment you push down on the accelerator it goes to 0psi and climbs from there as rpms build.
Now taking off from a stop the car will go from 20" of vacuum at idle to 1-2psi initially and will stay there until the mph has leveled off then it goes back into vacuum and you can hear the bypass "whoosh" pretty much all the time while its in vacuum at low speeds.
-Mark

Ditch that 'Bosch' valve and get a better/adjust type.

Its all crap now get me a bloody Turbo and let me show them what real power is all about (said in my best fat ******* voice)....

better...

Sorry,quote 'not so',You are better off with lower CR on a forced induction motor Vs the svt and better off with a milder cam on forced induction Vs the SVT.The same rules for nat asp motors re cr/cam etc etc do not apply on a t/c -s/c......please do a little more homework guys!

You missed his post Terry.

He said I missed CR in my summary. I was pointing it out for him.

I agree whole-heartedly that lower CR and higher boost will make better power.

It's just 9.7 CR at 10psi will produce less power than 10.25 CR at 10psi (barring detonation or course) That's what this thread was about originally.