Why has no one else mounted throttle bodies?

Ernie,

use a smartphone ap to determine your pre TB horsepower to see if there is a statistical difference. If you talk to Vince I think he said only got positive reuslts after letting the exhaust out. And then I suspect they would need more fuel to go any further. IMO to do any of this any justice you gotta go to a tuneable ECU otherwise I just don't see anyone getting anywhere.

 

The stock tbs on my car were hogged out 2.5mm which was the max we figured you could go and still have a functioning idle bypass. I think that's the little hole in the tb interior side. If more material came off, then that hole becomes a gouge and that's that and the engine doesn't idle or some such nonsense. Along with the reaming came a revised center pole that was aeroed for flow.

While I cannot claim huge massive gains in HP, I can tell you I have huge massive gains in available power and throttle response. That and the fact that the motor revs so happily that hitting redline was almost a regular occasion until I learned to be more sensitive with the right toe.

I think the cost of the work was around $400 for both tbs to be modified - a pretty reasonable deal for the result.

I am looking froward to the replacement cats.

 

Do you have any pics of the raised plenum set up?

 

I had the runners in the intake manifold ported and flow matched. They also radiussed the opening, inside the top of the plenum, where the tb opening is, so that the air would transition better to the plenum corners. Sharp edges are not good for flow.

Been waiting to do the tb's and now I have an excuse. I'll be sending them off to Rob Monday.

 

The info and pics are located here.
http://twinturbo.net/nissan/300zx/forums/general/view/2471246/Fun-with-the-CNC-lathe.html


The TBs were flow tested on a Super Flow 600 at 28in/hg. The throttle plates were held open at 90*.

Stock 50mm = 350.62 CFM

CNC oversized 54mm = 468.28 CFM

That is over a third more than stock! I was shocked at the numbers but I'll take it!




I think the 348 will see some similar gains....stay tuned.








Rob

 

Started another thread for the port job, as not to hijack this one anymore.

http://ferrarichat.com/forum/showthread.php?p=141011713#post141011713

 

The Bad Guy would have hijacked this thread.

 

your improved throttle responsive is not solely through massive power gains but the change of throttle opening area when you move to a larger throttle plate. this alters the indexing of "gas pedal. with the same acellerator pedal posting, motor will ingested more intake charge with the larger TB. please dont mistake this for significant amounts of added power to the motor, you are altering the amount intake charge for the same pedal postion.

along with deeper sound of the motor this is a very common perception to folks who swap out TB for larger ones. they often swear there motor is making much more power. until they slap it on a dyno, the gains are often much less then they anticipated. if the TB is not the bottle neck then it dosent make much difference how large you hog it out. the charecter of the motor will change though even if you dont more power. finding the max power for a given TB size is not so difficult. it will quickly show you what the limits of your motor indeveloping power.

 

Vinces RWHP gains were indeed dyno verified !!! So there was an actual measurable reason for the happy smirk on his face ....

The 200 cell cats are in progress ........ and we may be making another trip to the dyno after those are installed ......... I also need to baseline my 355 for the next phase of 355 HP endeavors .......

 

yes you already mentioned 5rwhp with enlarge TB alone with plenum risers...

 

At the risk of being controversial, I am of the opinion that regradless of how much you open a TB or add intake capacity, these engines are limited in their ability to produce more power by factors we just are not going to address.

Chiefly are the stock chips and maps with the 7500 rpm redline. We would need better engine management. Also, our cams/valve timning is not variable so we have to dial the engine in at where we want it to produce the most power and this may not represent the best balance for street driving and passing smog in socialist states, like CA.

Then there are the injectors which would need to be replaced with higher capacity versions and probably higher fuel pressure. This is probably not so much an issue on the aftermarket, judging from the mods done on the 358 race car. But then, the race car does not have to meet smog.

Don't get me wrong, this is a great exercise, but I, for one, am conservative on power gain expectations because I have been down this road apiece.

 

+348 ........

 

"What you mean we, white man?"

 

The voice of reason...

 

http://www.ebay.com/itm/PERFORMANCE-80MM-INTAKE-THROTTLE-BODY-CNC-BILLET-RACING-/260904302647?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item3cbf1bb837#ht_2648wt_1001



Is this "our" gothspeed?