Group Buy: 3x8 Throttle Body Mod + Plenum Mod

Also, with the smaller opening, velocities will be greater than with a larger opening. air has weight. F=MA. so the faster the air moves, the greater force it will have, which inturn equates to a larger pressure differential. Now with more pressure, there is a much greater combustion efficiency than with a wider opening. Thats why at lower RPMs the wider opening will make the car response very flat. So, stay with the smaller opening unless you have bumped up the compression ratio. Also, air compresses, so it will have no problem passing thru a smaller opening. the best thing you can do is to improve the restrictions such as the protruding screws and thickness of the throttle plate so turbulence is reduced.
john

 

if you supply more air to the engine, would the car increase the amount gas inyected? if you give it more air it's gonna need more gas or else you'll be running lean
also if you get more air in, you also need to take more air out, if not , there isn't gonna be any increase in HP or TQ

 

I agree with Birdman

The Injection system robs the 308 (both 2v and 4v) of some 35 to 40 + hp, the biggest gain you could get is to rip off the jetronic system and throw it in the trash can. There is nothing you can do to the intake system that will truly offset that injection system's damage to the 308's true performance.

Do what Russ Turner did and put 40 dcnf webers on it, and the job he did makes it look stock and fit under the bonnet.

 

Put carbs and cams back on................

 

Yup. I played with my car a couple years getting the breathing right. New headers made necessary all kinds of carb and timing adjustments and bottom line is changing one thing means you need to change other things as well.

I tried a less restrictive air flow into the carbs and it idled faster but it didn't drive as well by a long shot. Part of this may be the long convoluted air induction system my car has and needs for a uniform airflow.

I would be rather confident Ferrari knew exactly the optimum throttle body size for the whole system to work best. I would guess if you change it, you'll need to change a bunch of other stuff too and still not have a better running car.

Ken

 

yes, the very restricive mechanical mass air flow flapper will know and correct the mixture.

 

It might well be a waste of money, but it almost certainly won't do any harm either. The engines take a LOT of things into account when they spec a part ...and acounting is a big one. If an off the shelf part will work, but a custom part will add 0.5% more hp at a cost $200, you'll get the off the shelf part.

Putting a larger throttle body on almost any car I ever see dyno'd made more hp and torque right across the board. The down side is it make the throttle a little more sensitive and harder to control because a the same pedal movement gives a larger change in flow area. On my SC'd engine I use a massive oval throttle body, it flows something like 1600 cfm, like 3 or 4 time what a stock TB flows, but I use a progressive linkage to deal with it...the throttle plate moves faster relative to the pedal the further the pedal is pushed

 

For Ford and GM this is definitely true, but one would think with the MSRP of Ferrais being what they are, they spend the extra bits more often than not. I have no evidence of this however.

Ken

 

hahahaha ,thanks for the info!

 

308/328 model were under a lot of price pressure in their day to complete with Porsche. The CIS system itself was an off-the-self emissions fix and designed for much lower output engine. The whole system is undersize and what finally drove Ferrari to 4V engines to compensate, but it worked until EFI was developed to a point that it made sense….and CIS went in the trash where it belonged.

 

Mark, you said it wont do any harm but in the next paragraph you say it effects throttle response, makes it more sensitive, harder to control, sounds like a big downside to me and to top it off, you wont see a worth while gain if any at all. So in other words it aint worth it. Forced induction is a different story, Stevens car is not so your example doesnt apply, the rest of the system is the issue not the t-body, im surprised you of all people would say otherwise but now you have back pedaled a bit in your latest reply.

 

Maybe I wasn’t clear with what I was saying. Normally throttle response is about engine performance, but I was just talking about literally the way the engine reacts to the throttle pedal and how much motion gets what reaction. I mentioned my engine to say that even with a ridiculously big throttle body, the throttle pedal can still be quite manageable. My engine is making OEM hp at ¼-1/3 throttle and it’s not a problem to drive.

I think you’re 100% right though, we are talking about 1-3 hp for the throttle body vs 30 so due to the CIS and replacing the CIS would be a better place to spend time and money.

 

The big upgrade back then, was to buy the Weber "big throat" throttle body for the VW rabbit/scirocco. It was just a larger diameter TB to replace the stock dual butterfly unit. It gained about 4 or 5 hp, on a stock 75 hp motor...but made the throttle a bit twitchy, as some have surmised. It could be modulated better, if one added another (second) return spring on it, just to try and smooth things out. The ultimate solution later came out by Neuspeed (I believe), they used an Audi 5000 dual butterfly throttle body that had bigger primary and secondaries, and machined an aluminum adapter plate to fit to the VW intake maniflold. The REALLY trick set up, was to have your intake manifold port matched to the Audi 5000 unit so no adapter is needed. They also offered a Audi 5000 warm up regulator that had a vacuum port on it (stock VW did not have this function)....so under WOT it would automatically richen the mixture...added a couple more hp.

 

Is there a thread you can point to where I can read about what is involved in going from CIS to EFI as it would relate to a 308QV or 328?

 

Goto the CIS to EFI thread. Big thing in the porsche crowd that we can apply to f-cars.

 

Bigger is not always better, if it was, I'd have 6" diameter exhaust primaries and a 12" throttle body......got to look at the bigger picture....an engine is an airpump and it's how it gets it in and out as well as properly mixing fuel with the air for good clean efficient burn.....volumume vs velocity vs pressure, laminar flow, swirling, resonance, length of intake runners or trumpets, primary exhaust size/length/stepped not stepped, collector shape and size, combustion chamber shape, piston dome or concave shape, cam duration, lift, lobe centers, exhaust back pressure affect, sonic pulse, smooth vs rough port surface, port shape, valve stem shape and size, valve seat angles, 3 cuts, 5 cuts.....reciprocating mass, friction......etc, etc, etc....I can keep going page after page..... It all has to be looked at as a "system" and dyno comparisons before and after shows how one change or a combination of changes affect the "system".............that's really how you develop an engine, you can only theorize so much.....dyno base line run.......make a change......dyno again......compare data

Good analogy........"louder" is not a guarantee for being "faster"

I'd like to see data, does not cost any more to put a car on a chassis dyno than flow benching components, probably less..........

 

It seems to me that there are a lot of 308/328 owners that would buy a turnkey EFI system if such a thing were "packaged" and offered, similar to the way Nick packages and sells complete turnkey Electromotive ignitions with all the parts to convert a 308. Nevermind the performance enhancement, just the improvement in SOUND would be worth it!

Birdman

 

I think Nick sells the electromotive system pretty much ready to go.

I could probably spec something using a haltech E6X or maybe E8 for less money if you keep you fuel pump and distributors, crank pickups. It could include fit install injectors in the manifold and, fit fuel rail, fuel pressure regulator, sensors. But something complete like that would be about $2500-$3000+/-...maybe less if a few people wanted it. I was planning to spec something to try to put a basic SC kit together, it would be the same except the fuel injector size.

 

This thread talks quite a bit about it
http://www.ferrarichat.com/forum/showthread.php?t=76848

 

I think this goes right back to the off the shelf problem. I think VW got the samc CIS everyone esle did and it was designed for 150-200hp. It is probably not much of a restriction on a 75 hp engine, but is a huge problem on a 235hp engine. This is just a guess though, I don't have flow number to back it up other than a 308/328 gains about 10% more hp when you take it off.

 

The pre CIS 308 Ferrari (76-79) produced 245 hp (+/-).
The 80 -82 CIS equipped 308 produced 205 hp, the resulting loss in HP was directly related to the installation of CIS (minor losses were also due to timming and polution Eq. changes)
The addition of the 4 valve head on late 82 -85 308's boosted hp back to the 240 range.

With these #'s in mind it is easy to see that the CIS may have allowed Ferrari to meet stricter standards but in doing so robbed the engine of some 35 to 40 hp.

Rip the CIS off and replace it with Carbs! Imagine a 4 valve 308 with Carbs......Russ and I have.

Mini tennis balls assist in flow (Dyno #'s will prove this) as this cancel out effects of revision, it was Russ's Idea .......availible at Pet Supermarket.
We also think that it could make a great replacement for the old ping pong ball LOTTO machine.
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Paul,
Wasn't a big chunk of that 245 to 205 drop due to Ferrari going to a different SAE hp reporting/meas't standard.

If I remember correctly, the auto industry switched to a new SAE hp meas't standard in the mid-late '70s. Thus many of the detroit muscle car engines also took a big drop in their hp specs w/o any changes.

 

In addition to the shift in SAE standard, we've all seen various numbers quoted as SAE, DIN or the same factory number used with both standards. We all also know that the the early 80's 205 number was even quite 'optomistic', at best, in a grand Ferrari tradition of doing so. I guess if Ferrari was posting wishfull numbers, it doesn't matter what standard one uses...

 

That pretty much coinsides with what I learned in flow bench testing of the ENTIRE system, right down to the air filter system.
I found the 70mm TB flowed a handsome increase, even thru the Fuel Distributor. Period. Testing was purposely done in this manner to verify the validity of the increase, as well as to insure that the flow was not maxing out the Fuel Distributors flow, which would have resulted in a lean condition, and the resultant damage.
The 70mm size was shown to be a good compromise in increased flow, with out going overboard, as thios causes problems as mention earlier.
Dyno tests, as of yet are not available, as the last effort ended up with a waterlogged fuel system (due to a bad load of fuel purchased on the way to the rollers). The car did out perform any 2 valve injected car in the region, however, even though the tests were cut short. As the owner paid the Dyno Tab, it is up to him to post the sheets if he wants.
Interestingly enough the 2 valve injected motors greatest restriction is the horridly designed air filter housing, not the element itself, tests showed.
In short, I would be willing to bet that when testing does get done, there is an increase.
While an oversize TB is never going to compete with Webers, it isnt in the same ballpark as far as costs go either. Simple and effective, it is a step towards improved output.
Kermit

 

I'm pretty sure the change from gross HP to net hp was about 1972-73, and isn't a factor here.

When ferrari added polution stuff, they changed the cams significantly, so a 76-77 are 245 hp and 78-79 polution engines are 205. Then when they added CSI the hp dropped another 10 hp to 195. The Ferrari countered with the 4V engine which likes the mild cams and got back to 235...but removing the CIS still bumps it up 20-30 hp on a QV, maybe 35 or so on a 328.