rebuild...FI, Dual DCNF's, DCOE, or IDF?

tigeravg

tigeravg

True Classic
Rebuilding the top of my engine. Had dual DCNF's, went to another car. Liked them, loved the sound, but constant fiddling.

Why don't I see IDF's on our X's?

Any realistic advantage to DCOE's? I don't really want to hack up the trunk.

Can I make FI as fast and fun as the duals I had?

Bring it folks.
 
I'm an IDF guy, mostly because I have had pairs on almost all my spiders so they are my comfort zone. I had a rare dual IDF manifold for a 128 and ran dual 40s on my 128 track day/street car. I think IDF manifolds for Xs would be real rare and being taller carbs I don't know if they would fit under an X engine cover. Some folks will jump in and say IDFs are not meant for transverse motors but they worked fine on my 128. I'm sure the FI system is capable of big horsepower gains but it will never have the sound of four howling throttles. Others will jump in and say a four throttle body FI system is the way to go but that wasn't your question. DCNFs are obviously a bolt-on affair with good support here.
 
tigeravg said:
Can I make FI as fast and fun as the duals I had?
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Sure, if you go for throttle bodies, and have four individual runners.

If you mean by using the OE type manifold, not a chance unless it's forced induction...

If the motivation for IDF's is the availabilty of cheap chinese copies... caveat emptor.

SteveC
 
To me it all depends on what the car is being built to do; daily driver, occasional 'fun' street (only) use, combined track and street, or track only. Are we talking 'drivability' or 'all-out top-end performance'? I think the factory FI system will allow for the best daily driver - street manners. While dual carbs or full aftermarket FI (as Steve described) are better suited for track use. As a compromise to dual carbs, and in lieu of a FI system, maybe a good single carb upgrade? Steve has done a lot of development with that and can give excellent advice there. Although a compromise in performance, it would be much less of the "fiddling" you mention with duals. I realize this does not address your question of DCNF vs. IDF vs. DCOE, but my point is it really depends on your intended outcome.
 
One doesn't always need to use cheap Chinese copies of IDF's, why not use the real thing like what I have for my build.

Plenty were produced back in the day so there must be sets floating around.

IDF Sprint.jpg
 
RZSR X said:
One doesn't always need to use cheap Chinese copies of IDF's, why not use the real thing like what I have for my build.

Plenty were produced back in the day so there must be sets floating around.

View attachment 3157
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Tall carbs don't bother me (IDF's), I was planning on a cool mod to the squared-off deck lid anyhow. The car has some neat, albeit mild mods. Delta 400 cam, slightly larger intake valves and mild head work. Electronic ignition, light flywheel, PBS header, electric fuel pump, and a very well balanced bottom end. When she runs, she runs very smooth and has plenty of go (previous dual DCNF 36's). I had to remove the 36's to get another car finished, so it's forcing me to make a change...or not. I've never actually seen IDF's on an X. Wondered why. Porsche guys seem to love the damn things. The DCOE's have that annoying habit of running into the trunk firewall. Don't like that. I want to buy brand-new stuff, cause frankly i'm tired of buying second-hand crap (which always leaves some questions). I was also thinking I had enough cam and valve to support dual 40's, and may have been selling myself short with 36's. A used IDF intake would be fine, if I could find one, but real, new IDF's might be a nice change. BTW, I drive my car EVERYWHERE, in any weather. She's done 500-1000 mile trips on a regular basis. I will spend on her because she loves me and likes me to drive her hard wherever I take her. In 2015 my son and I loaded her up to capacity and drove 550 miles to Bonniville for speed week. We never saw RPM's south of 4500 all the way there and back. That's the kind of performance I expect. Next year my son will be 18, and we'll do the Silver State Classic. I'd like to be in the 100 MPH class and will need to maintain a tad over 5000 RPM's with my current gearing. Like a lot of you, this doesn't scare me at all. Just looking for dependability in fuel feed.
 
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tigeravg said:
IDF's ... Porsche guys seem to love the damn things
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Obviously also been very popular on air cooled VW's for many decades, so tons of support for them and very competitive pricing. Those guys also use IDA's if you want to go really big (but not practical for an X). It's been awhile since I've been involved in the air cooled VW scene but new 'real' Weber IDF's would still pop up from time to time.

RZSR X said:
what I have for my build
Click to expand...
Is that Sprint manifold a 128 unit? Set up looks good.
 
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