While the cams should give you a little less lag, there are other variables to it. One of these variables was that you went from 10.3:1 compression down to 9:1 which will increase the spool time. I don't know any math to estimate that to determine how much. By having a properly tuned VE map before and after plus the compressor map for the turbo would be the only true way to determine what the difference would be (with all other things being equal ie. wastegate spring, target boost level, etc.).

I am not sure what spring you are running in your wastegate but it will also affect spool up.

There are other things that can affect spool but based on the information provided, those are the only two that stick out to me. Remember, any time you do things to create more power, you typically sacrifice something. In your case, it may some spool time.

 

The size of the turbo doesn't really matter. Your motor is producing a different CFM at different RPM's, on a compressor map that is (more than likely) completely different than his compressor map. This does not mean one is better fit than the other however. While you spool quicker, his turbo could be running 15lbs in a more effecient island while you are spooling more effeciently but less effecient at target boost.

I am not saying that is fact, I am just giving an example of how two different builds, with two different turbos could act/spool differently not even including the tons of other variables that help/hinder spool time.

 

It is true that a lot of variables come into play however generally speaking a larger turbo usually takes longer to spool up, and mine is quite a bit bigger then his not to mention a much much larger a/r on mine. Taking into account both our static compression ratios and cams our dynamic compression ratios are very similar. Those two things are going to make the biggest differences and my guess is there's a lot left to be had in timing but not 100% sure

 

The general concept most people understand is that if you go with a larger turbo then you will not spool up as quickly. Just because this is what most people have heard/read doesn't make it "always" true.

If you go and spec a few turbo's for your car with accurate information, you will get an idea of what I am talking about when you chart the compressor map for your target boost level. Compressor maps vary A LOT from turbo to turbo. Finding a turbo that has the fastest spool AND the best effeciency is nearly impossible. Your usually sacrificing a little of one for another.

I personally charted at least 20 different turbos for our application and ended up having to get the guy from Honeywell (Garrett) who specs turbos for sponsored race cars to help us. What ended up being the most ideal was a GTX4294R. That turbo on our configuration will spool up to 15lbs by 3400RPM however, we are in the 60% effeciency island up to about 4000RPM then fall back in to th 60% effeciency islands by about 7000RPM.

As far as timing goes, tuners are not typically overly conservative at RPM levels nearly half of redline therefore I would find it extremely hard to believe his timing is far from MBT from 1000 - 4000 rpms... Especially since I am familiar with Brian's tuning on Osirus.

Other contributing factors making a difference in spool is the intercooler size, the piping length, piping diameter, exhaust restrictions, wastegate spring pressure, wastegate size, cam profiles, air-fuel ratio's and too many others to list.

There are many differences between engine builds, turbo kits and supporting mods that when people start comparing one build to another for the sake of "how they think it SHOULD perform", I just shake my head. There are just too many variables to make assumptions on what it "should" have made for power, how the torq curve "should" have looked, etc.

 

Nice try at cherry picking one source from a Google search that was reposted in a couple different forums. That thread doesn't discuss any experiences with the dyno at S&R/VSR either. I Googled "dynomite dyno vs dynojet" and found several links with a WIDE VARIETY of opinions and experiences on the dynomite dyno compared to other dynos (no shock there). Some said they read high and some said they read low. I found no solid consensus that the dynomite reads higher than other dyno brands. Hell, look at the huge variation in numbers amongst DJ dynos, and they are supposedly the industry standard. Within a few minutes of reading, I found numerous posts with experiences where a dynomite read lower than a DJ or another dyno. Here are a few examples:

http://ls1tech.com/forums/dynamomete...mite-dyno.html

http://forums.240sxone.com/showthread.php?t=27959

http://www.modularfords.com/threads/...ll-humble-you!

This thread had people posting differing experiences for high and low readings...

http://forums.evolutionm.net/evo-dyn...tang-dyno.html


So you have not provided any conclusive evidence to prove that S&R/VSR's dyno reads high. And I can only recall one or two of your DE customers on this forum who dyno'ed over 600whp with your kit, and they used 67mm turbos.

Bottom line: The OP's dyno numbers still refute prior defamatory statements you made in your negative marketing campaign to promote your own turbo kit over the top mount ST kits. Of course, trap speeds at the track are the best way to validate dyno claims. Regardless, it's cool to see another top mount kit making respectable pump gas numbers ...especially since one vendor on this forum has been asserting that such numbers are dubious and impossible to achieve without a T4 housing. Congrats to S&R/VSR and the OP.

 

We have had our car on multiple dynos S&R's Dynomite, a brand new (at the time) Dynojet, Top Speeds dyno which I think was a dynojet and was fairly new and old dynojet at a shop I will not mention. The ONLY one of these 4 that was off more than a couple HP was the OLD dynojet. Not going to mention who had it but man, it was nearly 30whp higher than the rest.

I am not saying all dyno's are equal, I am just pointing out that S&R's dynomite and "new" dynojets read within a coupe hp of each other in our experience.

We had our car at 648WHP with 14PSI on pump.

 

I'm still running the original 7lb wastegate spring. We're planing on replacing it with a 12lb spring soon.

 

Yeah, going to the 12lb spring should help your spool. Since that is close to your target of 14.7, make sure your boost controller is configured properly so you don't get boost spikes far above your target.

 

I don't know if these will post. I'm not too familiar with posting videos. If they work these are a few videos of the car on the dyno.


https://www.facebook.com/photo.php?v=599240133426470

 

Nope. Easier to upload to Youtube or Photobucket.

 

Hope this one works:

 

One more:

 

There are actually mid 600 on the 6266 on pump gas. All of the ones with the smaller 6262 are stuck under mid 500's. What's the difference? the size of the exhaust housing. Makes a huge difference in flow.


Nice numbers though! I'm sure it would matter what gear the car was in unless this is a load based dyno. If it's a non-load based and it was used in a low gear it would cause that power shift like that. I guess it could be the backpressure on the turbine side that causes a little later spool.