I know that, I've just never seen a dyno of a Z with a cosworth in which it really affected top end much. All the dyno's I've seen (not many) have it gaining the same power in the midrange as the top end. While that's all fine and good, it doesn't show me that it flows extremely well with lots of air being pushed through it.

 

Hal showed me his before and after dyno of his personal car and it gained a pretty significant amount in the top end, enough to make me buy a Cosworth manifold

I don't know if he will share that dyno chart though

 

Contact Sharif or Sam...they did some testing on the Cosworth vs Stock and the findings were heavly in favor of the Cosworth....Top end was where it stood out

 

I picked up HP above 4k rpm, but it was not an apples to apples comparison as I made additional changes to my build as well.

 

Yeah...thats where it comes in....I know either Sharif, Sam or Hal did one with swapping plenums.....The cosworth did well.

 

Same car, same dyno, same boost, same tuner.

Each block on the dyno chart represents 20hp/tq, so you can see the gains are as low as 20 and high as 40+whp. Any time I can pick up 40whp on the same fuel I am thrilled! I have seen this similar gains multiple times now.

 

well...i wish you had tested it with the gt47r on the dyno....
doing my "own" testing with a 76mm.....your dynosheet is encouraging.

 

Now that's more like it....Cosworth manifold...here I come

 

will u need a retune if u just add the new manifold with the same map?

 

Yes, but not a complete retune. Full throttle fuel and ignition would need to be adjusted but this is not difficult and does not take long.

 

still would love to see spacer vs cosworth.

 

I have done this and believe it is posted somewhere as well. Regardless, you know what gains a plenum spacer makes compared to stock, and you know what Cosworth makes compared to stock.

I also appreciate how the Cosworth cleans up the engine bay and allows for easier access to spark plugs.

 

i dont ever remember seeing a spacer run out past 7500 rpms though. What cams are used in your comparison dyno above?

either way, nice data for getting that plenum!

 

EXACTLY !! Thats one of the things I love about it...even I can change my spark plugs now

 

"How does this thing perform compared to a spacer?" is the most common and important question that has been asked for over a year. It is surprising and frustrating that there is still a lack of several independent comparisons between the available spacers versus the Cosworth. It is something that has been requested since before the release of the Cosworth plenum, yet not even Cosworth has shown an effort to prove the performance gains versus a spacer. And the shops that sell the Cosworth plenum don't seem to be very eager to publish many comparison dynos with a spacer involved.

 

LOL I don't think the forum community has seen hardly any VQ's revved out past 7500RPM with or without a spacer. Setups with big enough turbos that don't drop off before 7000RPM have been few and far between. There is also a lack of dyno comparisons for stock versus spacer in builds making over 650whp.

 

Someone posted Stock Plenum VS Spacer on here.....its been a while back...but I did see it...dont remember the exact numbers...but I think it was between 6-8 whp gain on an FI.....Not sure if it was checked or backed up...

I know Sharif gained over 40whp on my Cosworth vs stock....So I would say 32 to 36 whp over spacer if you use those numbers

 

ya, but the spacer gains were in the stock powerband (under 6500 rpms). The cosworth isnt making 1000$ worth of extra power under 6500 rpms. Above 7300+, it looks great though.

Seems aggro cams and 7500+ rpm redline are in order for the Cosworth to shine.

So you dont need to move the Cosworth at all do change the plugs. Thats really nice.

 

I'm going to speculate that the rpms at which the Cosworth comes alive is dependent on the rest of the setup. On my build we had JWT C2 cams, and we picked up HP lower in the rpm range. I do say this with hesitation, though, because when we added the Cosworth we also added turbo blankets, the pathfinder cooling mod, and other little tweaks here and there.

 

Here are my dyno plots with both the Motordyne spacer and the Cosworth plenum. Unfortunately, these are at different boost levels and with the changes noted above.

Notes:

1. The first one was run on a hot day. Measured RWHP was in the 550's but it weather corrected up to 584 RWHP. The second run was on a moderate day, it measured 609 RWHP, but weather corrected down to 603 RWHP.

2. The person on the first tune (Jack) opened the throttle later than the person doing the second tune (Roger).

3. The dip in the second plot at around 4200 rpm was intentional. The timing was pulled back here and we ran it a little on the rich side to provide safety margin. I was supposed to run homestead the next day (I over-reved the motor playing with WOT shifting, so I didn't make it).

4. I think the torque plateu at 5000 - 5600 rpm is due to the cosworth. Specifically, I venture to say that this is the rpm range at which the Cosworth intake runners are tuned.