New to Mechanical Fuel Injection on a -6, How to replace air box for ventures? Options

[R8CERX]

Ok. (IMG:style_emoticons/default/piratenanner.gif)

I love the new race car; 914 with a 2.7 RS engine and Bosch Mech Fuel Injection.
Race it twice and is plenty fast and powerful that I am not even maximizing its potential.

I still got the 205-50-15 wheels with 200 tread wear..and oh boy! I am ice skating everywhere! so I have learned to keep it slow to go fast! this is another story for another thread about tires!!

MY CURRENT ISSUE:
I hate the lack of sound--I still have the one single out muffler and the air box on top of the fuel injection ventures.

I am all ears for your advise in how and where I can buy the necessary hardware to get rid of the air box and put open air stacks (with perhaps a mesh on top) so I can hear the low sound better?

also, I got a pair of two megaphones, that I plan to put on the exhaust, and take the single outlet muffler--if this becomes too loud (specially for autocross or track events), I may just have the muffler converted into a double exit vs a single one.

I am open to all of your suggestions!!

I am a driver, not a real hands on mechanic, so keep it simple and stupid..... (IMG:style_emoticons/default/confused24.gif)

[ClayPerrine]

I am moving this to the garage, as it belongs there...


What type of Mechanical Fuel Injection do you have? Is it from a 911T, a 911E or a 911S? Does it have plastic injection stacks or Magnesium ones?


If it has plastic stacks, there is not a lot you can do unless you can fabricate something. Don't run it without the air cleaner, that will screw up the engine in a hurry, plus clog up the idle bleed ports in the throttle bodies.

If you have the Mag stacks, you can use the K&N Watershield air filters for a carbed 911. You have to trim the inside rear of the top of the RH one to clear the injection pump, but the rest is a bolt on.

For your exhaust, I suggest the Bursch 911 MFI muffler setup. It will meet the DB requirements that are present at most AX locations these days. Plus it adds a little bit of HP, and it sounds great! Putting open megaphones on it may just keep you from running.

Be aware that MFI is sensitive to both intake and exhaust changes. Just changing the back pressure will necessitate changing the mixture settings.

[Cap'n Krusty]

As an old guy who was around when Roger Bursch's stuff was all the rage in So Cal, I can tell you that the HP increase has been measured to be negligible. His muffler simply moves the power and torque curves up the RMP range. IOW, it's still there, just not where it was before. The design of the engine (lotsa valve overlap) requires quite a bit of back pressure in the exhaust. Especially with the S, and the E as well, the "free flow" is actually detrimental to the way the engine runs, and mixture changes are in order.

Might be OK for a dedicated track car where you're running up close to the rev-limiter all the time, though.

The Cap'n

[Dr Evil]

Venturies are what you want, but the Ventures are cool (IMG:style_emoticons/default/cool_shades.gif)


https://www.youtube.com/watch?v=VIoRMrxXbbI

[Eric_Shea]

Keep the factory air box. If it's all about noise, get some earbuds and an mp3 of a 906 revving to the limit.

You could go with the stubby snorkel from a 73 MFI assembly. By ditching the warm-up box the snorkel itself is basically wide open to the filter.

Danske makes a sport muffler with dual out that bolts right up.

I'd simple enjoy the ride. That's a bitch'n motor in what looks to be a bitch'n car. (IMG:style_emoticons/default/wink.gif)

[R8CERX]

mmm...
it is all about the grawl...I love the sound of my original six 2 liter... (IMG:style_emoticons/default/blink.gif)
but not fast enough!!

yet the 2.7 with the air box is just not right! Is like having a wife with a nice set, and she hides them all of the time....!! (IMG:style_emoticons/default/headbang.gif)

also, the lack of seeing the beauty of the engine underneath the big black hunk of air box is really depressing... my 2.0 liter has the nice weber 40 IDA and KN filters, and the noise and looks!! I would sleep in the car if I could!!

so, i got a fast car that lacks the sound and showing off the nice engine itself--

anyone here has the set up I am looking for? meaning pictures of what I want?

such as:
the VENTURIS (Thank Dr Evil...but my auto spell seems to like ventures better!) with a filter media on top and high velocity stacks?

I am taking notes from all of your suggestions to start planning next move. (IMG:style_emoticons/default/piratenanner.gif)

I do appreciate the fact that I did not know that once I start messing with the muffler, I guess for MFI it may affect it--so I will keep a close eye on this

Please, pictures of what may work, will help!

Since this post was moved to the technical side, I guess I cannot ask for pictures of nice set ups with some female models along the way.. bummer!!

I do have to keep the velocity stacks under the height of the grill cover.... (IMG:style_emoticons/default/dry.gif)

[Eric_Shea]

What's the "DB" level you're shooting for?

[MDG]

What's the "DB" level you're shooting for?

dB level I'd say he's shooting' for 85-90.

DB level he's closing in on open neck and gold chains I'm afraid. (IMG:style_emoticons/default/unsure.gif)

[Eric_Shea]

Correct. (IMG:style_emoticons/default/wink.gif)

[campbellcj]

I still got the 205-50-15 wheels with 200 tread wear..and oh boy! I am ice skating everywhere! so I have learned to keep it slow to go fast! this is another story for another thread about tires!!

MY CURRENT ISSUE:
I hate the lack of sound--I still have the one single out muffler and the air box on top of the fuel injection ventures.

Where are you located specifically? I would be glad to meet up sometime if feasible and share whatever little tidbits I have learned over the years. Are you doing (or going to be doing) wheel-to-wheel racing, time-trial, or autocross? I will be out at Willow Springs Sept 6-7 (POC) if you want to come scope that out and talk shop a bit.

I agree with the other guys about the airbox and muffler. My current 914 is carbed but I had a 911E (2.2 MFI) for many years and went through some of what you are asking about. For the muffler, a Dansk 2-in/2-out sport muffler based on the factory design is a great option. They are not terribly loud, and pretty well made (not cheap though.) The MFI system is finicky about exhausts as the Cap'n noted but this one works well with it. Frankly though, on that 911 street car I tried several different mufflers and ultimately went to a stock type 2-in/1-out "sport" version that AJ-USA sold back then. I believe it was just a stock design with slightly less baffling inside to make it sound more throaty. I highly doubt it improved power noticeably.

The popular airbox replacement option is the K&N filter with either flat-top or watershield covers. I do not know what mods you may need to make for MFI as they are really made for Webers. Doing this will significantly increase sound/noise, make the engine look MUCH better, and reduce filtration efficiency vs. the stock airbox.

You may want to talk to Marco Gerace at TLG Auto in North Hollywood as he had an MFI 914-6 for many years and is rebuilding it again now, I think.

You are definitely gonna want to do tires. I have a very strong modified 2.7 in my car and it was very tough to drive on 205 tires...even Hoosiers. I can't imagine racing on hard street tires.

Good luck and have fun!

[IronHillRestorations]

The factory intake is very well engineered, as is the exhaust. I'll 2nd the Cap'n and the E man.

[sixnotfour]

K&N style will work if you enlarge the holes in the base plate...drill 4 holes for bolts..

[GeorgeRud]

You could add a sport muffler ( original banana type muffler with two exhaust pipes sticking straight back in the center third of the muffler). As mentioned , they're available and there are also instructions out there that show how to modify an original muffler if you're good with a welding setup.

I'd try to see someone that has that setup so you can hear it actually run. The sport mufflers can get obnoxious for a street car, but might be OK if it's just for autocross. My 2.7 RS with Webers under Watershed air cleaners and a stock muffler sounds sweet without being to loud (I can almost hear the radio, almost!).

[R8CERX]

FOLKS- I have not forgotten! thank you for your advise! (IMG:style_emoticons/default/drunk.gif)

Sorry for the lack of my response to your advise; currently I am in hospital and will respond with more time once I am out. (IMG:style_emoticons/default/barf.gif)

I am taking notes and really appreciate the advise- (IMG:style_emoticons/default/cheer.gif)

Will respond once I get out...

They call my number---time to go for some happy gas!!! (IMG:style_emoticons/default/blink.gif)

[R8CERX]

YEAH!!
I am still alive! live to race another day! (IMG:style_emoticons/default/headbang.gif)


Here are the responses and take aways I made from your comments/advise:

ClayPerrine:
The car has a 911RS MFI with plastic injection stacks! (IMG:style_emoticons/default/mad.gif)
Agree-I should not run the car without any protection.... (IMG:style_emoticons/default/sheeplove.gif) (IMG:style_emoticons/default/av-943.gif)

Exhaust, I currently have a banana muffler that could be converted to a dual tip--plus able to use the megaphones at certain places such as fontana, from what I understand.

The decibel max for PCA San Diego is at 93dB; thus the banana conversion may work out.


Cap'n and 9146989:
I got the message--I have only ran the car with the banana single out in 2 autocross events; going to Fontana this sunday, and plan to change the banana to the Megaphones--do you think it will throw the balance way out for the car to not work (engine) well?
Previous owner seems to have changed back and forth with no major issues.
Let me know--worse case, I take both mufflers out to track and change it back if needed.

Dr. Evil: (IMG:style_emoticons/default/bootyshake.gif)
But get ready, my tranny is grinding in first gear and sometime second gear---I see myself slowly coming to the master....... (IMG:style_emoticons/default/pray.gif)

Eric:
I have the Bose noise canceling headphones--will try them over my helmet... (IMG:style_emoticons/default/KMA.gif)

HEY!! there is an idea!! start selling noise canceling helmets!! (IMG:style_emoticons/default/beerchug.gif)

I will check out what the stubby snorkel from a 73MFI looks like--thanks for advise (IMG:style_emoticons/default/biggrin.gif)

Agree--car is way over my head for me right now; still learning about it! lucky, previous owner and member on this site is the coolest cat--and supports me when questions arise. (IMG:style_emoticons/default/aktion035.gif)

MDG;
85-90 dB was close----it is 93dB
Open neck and gold chains..... I am ESL (english as a second language)--over my head? (IMG:style_emoticons/default/confused24.gif)

Campbellci:
I am in Murrieta, California
Plan to autocross it and also TT/POC events (wheel to wheel)
As I am still getting the car sorted out (meaning, putting lots of non-available DINERO on getting all my ducks in a row), I will do my best to make it to Willow Springs sep 6-7.

Just bought me the Hoosier SM7 (R7) tires--I figure that they are a must over the 200 Tread Wear I got now.
I will be selling and if anyone is interested, a set of FOUR KHUMO tires (basically brand new)--will post in classified adds.

Sixnotfour:
Nice pictures--thank you! I like the set up, but since I got the plastic unit, I will need to evaluate this change further with pictures or anyone that has a car near by to check out what they have done.


GeorgeRud:
I think this is the path I will follow--convert my banana into a dual tip exhaust.

Thank you all for your advise!


PS-
Where is Woodruff when I need him???? (IMG:style_emoticons/default/confused24.gif)

Check out my shoes after I finished my last autocross... I drove so hard, that my shoes could not keep up with me.....!! (IMG:style_emoticons/default/av-943.gif)

[Eric_Shea]

Where is Woodruff when I need him????

Purdy sure Woodrow avoids threads with "How do I make my MFI louder?" in them. Mandated in technical training 101 manual for P-car mechanics. (IMG:style_emoticons/default/biggrin.gif)

[Cap'n Krusty]

Yes, the megaphones will result in mixture changes and probably degradation of performance. But that's OK, we all preferred noise over performance at some point in our autocross/time trail days.

The Cap'n