Enlarged Throttle Body – A DIY Product Review

Looks interesting.....but what I always wonder about modifications like this (which are very easy to do & cost basically nothing) is that if it was so easy to improve the car you'd wonder why Ferrari didn't do it themselves in the first place.

You would think they must have tested different configurations on something like this.

 

I'm real interested as to the results of your modification. Please keep us posted. Looks like nice machine work on the parts. I did this same mod to one of my bikes. I kind of think you will maybe notice more of an upper end change rather than lower. You might need to adjust the FI unit to run richer. After some breathing mods on my 308 we needed to reset the mixture. There was a big change in power after the engine was allowed to breath. What pipes and muffler will you be using? More air in won't help unless it also gets out.

 

Good on you for doing this, Dave. I know Mike and Tommy tried this a few years back with negative hp results but I think that it's time for a redo. It will be very interesting to see how it all goes and the different solutions you come up with.

 

Dave,

Great write-up!
Here's some reading for the cold evenings..

http://www.ferrarichat.com/forum/showthread.php?t=346701

Regards. Ben.

 

+1000

Ferrari do know a few things about engine design. It is unlikely that they did not size the airflow to match the fuel delivery maximum (metering plate right down) at wide open throttle.
To confirm that they did indeed get it wrong, it would be necessary to test on a rolling road after fitting this to ensure the mixture is not too lean at WOT otherwise burned valves could result. If it is too lean, then the fuel delivery would need to be increased. Not sure how you would do this if its maxed-out already.
Even if it is not too lean, what difference would increasing airflow make if the fuelling is not increased? Air on its own does not produce engine power!

 

Dave, I think it looks cool as hell even if you find out that it doesn't quite add 30hp. Good luck.

 

There are several factors as why Ferrari didn't do this in my opinion.
1. driveability. With a larger bore you will flow more at any T angle past zero. Not that it is uncontrolable but I deffinitly noticed my mustang was more jerky when I went to a larger throttle body.

2. Port Velocity. Although more volume a larger T body will slow down the velocity of incoming and that can effect cylinder filling especially at low valve lift.

3. Cam profiles. The cams in the CIS engine are not the greatest and choke the engine far more then the intake system does. I would be interested in seeing before and after of the total system on the flowbench.

Newer engines are running larger throttle bodies the the older ones but look at the power output they are making as well the cams are better shape and variable timing make big differences. Compression is coming back up on engines do to combustion chamber shape as well as fuel managment.

I am interested in seeing the results and if it works I will may try it on my engine.

 

Please don't misunderstand me, I'm not knocking this & I'm interested in what the results are too.

But, this was kind of what I was alluding to. The whole system is a callaboration of things that work together. Of course the engine could ultimately produce more power than it does but as a manufacturer they have to provide driveability and reliability as well as performance.

Nonetheless, if there was a clear benefit to be had by doing this that didn't reduce driveability & improved performance I am sure they would have done it. Interesting questions also as to whether the injection system will be able to keep up with it at WOT and high revs as well. If the thing starts to lean out at the top end because of this, that would be bad.....

 

100% agreement my friend. I think it has been well versed on this form that there is no magic bullet to make our cars a magic bullet. Most of our cars especially the US market ones were built in an era where the politicains got involved and did what was best for us little people that can't make decisions on our own. Ferrari had to play the hand they were dealt. To really improve these cars you need to adress every part as a package. I do not worry about these cars leaning out after looking at turbo/super charger packages out there making 350+ hp w/out modifying the CIS.

 

Nice job Dave.

Had the throttle bodies on my 348 ported late last year. (the thread Ben348 posted a link to). The throttle response is better, and I may have gained a few more ponies. Don't know for sure because I never did before and after dyno's. Never the less I'm glad I had them ported and would not hesitate to do it all over again.

 

Let 'er breathe 90mm tb with 1" added to plenum height. Works great. Note: Also EFI and minimum exhaust.
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Doing this and fitting EFI is a whole other ball game and makes a load of sense.

 

Yes you are right, the evidence does seem that there is plenty of headroom on the CIS. I stand corrected on that!

 

What size is the QV throttle body?

I think the heads are the same (or nearly) between the carbed and the 2vi. Seems like there is alot more opening with the carbs. Course they also dont have the giant flapper in the air stream either.

Aaron

 

That's just great, glad it worked out. Any increase in the fun factor makes it worth it. I too would be curious to see some dyno info. Any data on fuel consumption changes?

 

Enlarging the TB on a 308 will cost you hp, I think around 7 or so.

I have a Durable 1 enlarged TB on my 308. Back in Jan 06 Mike C and I pulled a few Dyno runs with and without it. The results show that you need to leave it alone.


Want more quick cheap hp, but a K&N. We proved that.

http://www.ferrarichat.com/forum/showthread.php?t=88743

 

For what it is worth I like the 308 just as it is and enlarging the TB won't help when a ZO6 pulls next to you. I've had my good times in Vettes and Jags but even with the lack of HP the F-car has THAT special feeling that other Marques could not supply me with. Lost

 

I forgot about that.

The evening before I left my belt broke (again) on the alt/wp so I just unbolted the TB and took it to Huntsville with me in another car. As you correctly read, we put it on Mike's car for the test.

My car has the manifold matched to the TB so I am good there, I just don't know the dyno #'s because we never tried it again with my set up

 

Interesting upgrade. I have to do some more research. Thanks

 

Late update on my ported tb's.

Did a before and after dyno test last year and they were good for +4hp to the hubs.

 

This doesn't surprise me... A lot more goes into the dynamics of the intake charge than simply the bore diameter. A larger bore will usually reduce the intake velocity, which can reduce the density of the air charge. The original designers may have even "designed in" very specific turbulence and swirl characteristics.

I once spent countless hours with a dremel tool "opening up" the ports on an old set of Sportster heads. This resulted in an extremely embarrassing visit to a dyno in front of a large crowd of spectators at a bike show...

At least it sounded good on the dyno!

However, I still enjoy seeing people trying stuff out, even if it doesn't always work!