Project VF Part IV - The Need For Speed Continues...





After fitting the SQ57 we decided it was time to get a decent head onto Project VF. Now don't for a minute think that we aren't a major fan of the LS3/L98/L77 port configuration as nothing is further from the truth...we love 'em! But as good as GM has them we set about the task of improving on it with the MAST 4.0. The 4.0 is based on the MAST Mid LS3 cylinder head but we closed the chamber back to 4.0" bore and moved the exhaust valve to the bore wall thus unshrouding the intake valve. We have tested ported LS3 casting both hand and CNC for very little gain and little improvement in seat of the pants driving. Part of this we felt was because of the massive volume of the LS3 intake port casting, which by the time it is ported pushed up on 280cc...low air speed for cylinder fill on the closing side of the camshaft the 4.0 head was born with 255cc intake! SQP being MAST Factory appointed distributor for MAST Induction in Australia identified that the Aussie market is basically 6L dominated. After some conversation the new design was decided on and put into production. Can the grey importers have made what they want? No!! This head is only made in limitted batches for SQP.

Theory aside...onto the engine they go. We stopped with the SQ57 cam as it was getting real tight on piston to valve clearance. The MAST head has drop height to spare so cams upto 260@ .050" can now be used if desired! We will start with what we had in there- the SQ57 so we can do a true back to back.


Apart the big girl comes again...




No "eye brows" shows the SQ57 was safe...just tight!





These bad boys are just itching to get into the mix!





How pretty is this picture?





Enough talking...lets get it done!





OEM standard intake utilised at this point...we are proving the cylinder head so one change at a time.





Rocker pair on for geometry check and lifter preload.





Travelling through .650" lift and leaving a pattern no wider than the width of the roller...we have the geometry pegged!





Yella Terra are a great company to work with. We have had proto typing and production pieces in operation for every MAST cylinder head bought into Australia. Utilising a light weight design, rpm potential isn't hampered as with some of the USA rocker brands leading to valve float at around 6000rpms. Thank you YT for your support. They are pretty and they work!





Fitted a set of Holley covers just to bling it up some...I like 'em!





All back together and ready for the dyno. As the photos show, the only change has been the cylinder heads...we have kept the same size pipes, OEM intake manifold and the same camshaft.





 So How Did They Run Up?



With just a head change out, we have gained just on 15rwhp through the A6 auto. No other changes but ECU recalibration. Essentially changing the heads is the same sort of increase on the dyno as the SQ54 to SQ57. So we have increased the breathing of the engine as if we had fitted a larger camshaft. 15rwhp doesn't seem like a heck of a lot of extra power but it needs to be kept in mind that the LS3 head in standard form is very good...the number of fast cam only cars shows us that. Also we are far from optimising the package to suit the new cylinder heads. Bottom line; we inproved the ability of the engine to move air with a smaller, smarter head...midrange torque is up as is peak power!



To The Track...



Shane took Project VF to the 'Plex to test the gains seen on the dyno by the MAST 4.0 head upgrade. First thing he noted on the drive to the track was how the engine was so much more responsive and willing with smalll throttle movements. But what about WOT?



 Straight of the bat it improved by 1.2 tenth and 1.3mph...



Above is the best run of the night...11.59@120.48mph. That is a gain of .12 seconds and 1.75mph! Now that is one damn fast street car in anyones book. To confirm the weight of the lard arse we had ANDRA put it over the scales and with driver, it comes in at 4011lb! Using the old speed calculator method we are now making an average of 540hp at the crank....up from the 510hp with cam only. That is an increase of 30hp with just a bolt on. How come the dyno only showed 15hp? Because we fell into the trap of not looking at power under the curve...we fixated on peak! This is the common mistake in the market where punters head from shop to shop looking for more peak power for the buck...just a dyno graph will do! Sad when peak power is only part of the equasion to moving mass over distance. We have increased average power over the distance to the point where we have an 11.50s streeter that idles at 800rpm.

It should be noted that with Project VF we still have a very tight converter and relatively tall rear ratio. It is a street car and we are trying to put together a step by step approach to making your street car fast...not turning it into a race car. Sure we could slip some 4.1 gears into her with a 5000rpm converter and hit the low 11s with the power we have right now but who wants to drive that crap around on the street? Might win the pose comp at KFC but we will pass on that thanks.


Next? Lets optimise the 6.0L to get the most from those trick heads...keeping the cam where it is, we will upgrade the intake and 1 3/4" headers and see where we are held back. Stay tuned!



So Big Is Better?





 As promised we have set about trying to increase the efficiency of the combo now via some header and a manifold change. The headers came first. Why? I had some in stock and reckoned it was as good a place as any to start. Now I haven't taken a bunch of photos for a header change but we have gone from a 1 3/4" primary Di Filippo header to the same brand in 1 7/8". These are a straight bolt in and no cat or other exhaust changes were required. As stated previously in Project VF, I have always felt the larger pipe lost low end torque and some seat of the pants acceleration. To reinforce this theory on streeters and I was so confident of it I had all our MAST 4.0 heads made with an exhaust port configured around a 1 3/4" pipe. Airflow improved marginally with a larger pipe on the flow bench even on the small port...what this showed in the real world would be interesting.

So pipes are on and we took it to the dyno...sometimes it can be hard to see a gain and sometimes you can look for a gain that wasn't there. The dyne showed it lost power at peak and through the rpm range yet when the tune was optimised it showed it wanted more fuel but no extra timing was needed. This would start to indicate that we are now over scavenging the intake (putting theintake charge out the exhaust) and that no timing was needed showed we were already evacuating the cylinder cleanly....very interesting. Why no graph...ask Dyno Dynamics why the last session on the dyno is missing from the storage files??? Got to love their crap digital software...drives like Mr McGoo and as reliable as rain in a desert. Where did my old analogue dos based machine go? So...we will let the track tell the story.



The result is the above time card. Now how can that be...the car LOST  2 tenth and 2 mph! But what killed us was through oil downs and rain...we only got one run so couldn't categorically call it as a result so we had to sit tight and wait for another opportunity to hit the track again.

That came last night at the Fast Friday...Shane headed to the track to put this puppy to rest.


The air was far better than last attempt so power should be there...




It was still slower...




air was coming around and better than any we had ran in this season...

but the PB was out of reach both ends of the track...



Well that pretty much seals the deal on the big pipes. Very safe to say that they definitely made the car slower. The 60' increased as the lost mid range power hurt the car getting out of the hole.Clearly average power was down as well as we didn't even get a gain in the top end speed. Clearly they are a step backwards on this size engine and this weight car. Got big pipes on your stock cubed car? You now know how to make it quicker! SQP has always recommended 1 3/4" pipes even on mild strokers. We have always felt they gave better seat of the pants acceleration...seems the old butt has a pretty good gauge reading when compared to the black top dyno. 1 7/8" make your VF faster...MYTH BUSTED!


Hopefully we fare better with the FAST Intake! Somehow I think we will as any increase in intake flow is generally rewarded...Stay tuned!




<< Project VF Part III - Let The CAM's Continue...

Project VF Part V - The VF Chronicle Continues... >>