What is best way to retrofit carbs onto GTSi Engine ? | Page 2 | FerrariChat

What is best way to retrofit carbs onto GTSi Engine ?

Discussion in '308/328' started by [email protected], May 29, 2021.

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  1. andy2175m4@yahoo.com

    [email protected] Formula Junior

    Dec 7, 2008
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    Los Angeles, CA
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    Andy Rein
    Enlarged Throttle Body – A DIY Product Review
     
  2. smg2

    smg2 F1 World Champ
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    I'll add after having been down the SC road numerous times. One can safely add 7-10psi on a stock engine. The low compression and wet noodle cams don't let compression get high enough to be a problem. It'll add decent power and make it worth the cost.
    Turbo, easy 7psi on stock. But managing heat will be the top priority.

    We're at the moment working on getting a cam package together for stock engines that'll bump bottom and mid for street driving. It'll also include new springs and retainers. I get a lot of std engine build requests for more bottom end tq, and passing power on the street without having to scream at redline. Sure the sound is fantastic, except here in CA and I'm sure other places it's a quick way to get flagged for a ticket... yrs ago I got ticket like that, was told " you sounded like you were speeding" fought it and won, but still a pita. And let's be honest, these engines are woefully lacking bottom/mid tq, esp the early 2v injected.
     
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  3. Rifledriver

    Rifledriver Three Time F1 World Champ

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    An increase to around 11:1 works wonders.
     
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  4. smg2

    smg2 F1 World Champ
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    That's the sweet spot. Beyond 11:1 has diminishing returns unless........

    Something like a decade ago we did a 13.75:1 QV build, ethanol only. 4L, Cams,etc.. boy howdy did that thing move! It would pull from a dead stop in 4th gear, like 1st in a stock QV. Big undertaking, but client request for ethanol. Good thing GM has affordable inline ethanol sensors. Saw variations of 85% to 100%
     
  5. Rifledriver

    Rifledriver Three Time F1 World Champ

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    My 3.5 liter 328 has nearly 11 and the Microplex in the most advanced setting. On hot Texas days it never has a detonation issue with pump gas. With different induction and cams it may be a very different story. Like in NASCAR, you can squeeze a little stuff real hard.
     
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  6. derekw

    derekw Formula 3
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    Andrew, I did the drawings and printed a prototype to fit IDFs or IDAs to the 2V head but the moulds were complex and expensive for a short run, and there was little interest. I might make a set of two for myself (cnc the flanges, cast the tubes, weld together.) I bought Chinese copies of the IDF40s for about $120 each— lots of parts for tuning as all the VW and early Porsche people use them. My guesstimate on the price of manifolds is about $500/set plus a bit for linkages and a water crossover Tee. You could also fit EFI throttle bodies to these manifolds.
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  7. smg2

    smg2 F1 World Champ
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    Honestly the BIG problem is CA emissions testing. Unless the OP plans on never driving on the street... It's a non starter. Going from CIS to carbs is illegal here, regardless of how clean it runs.

    Best to find a carb 308.

    Heck even swapping out the CIS for modern EFI is a no-go. Forever 1976 and newer will be smog tested.
     
  8. Rifledriver

    Rifledriver Three Time F1 World Champ

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    Even carb 308s can be a big enough problem I would not have one in California. As I recall the tail pipe measurement is the same for all and standards changed a lot from 76-79. As I recall the numbers were at one time lower than the standards the cars were built to.


    One more reason I'm glad I'm gone. All our cars combined cost less to register than any single one in California. None of the Italian cars needs a smog either.
     
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  9. Kidasters

    Kidasters Formula Junior

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    Amen to that. I got Antique plates for all the "toys". Only get plates every 3 years and no inspection.
     
  10. smg2

    smg2 F1 World Champ
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    Yup, they keep tightening the numbers. My dd Mercedes is getting harder and harder to pass.. it's a '91 and runs cleaner then when it left the factory. Had to replace the cat at 250k miles... What CF PITA that was!

    As much as I want to stay here, it's beautiful on the coast... It's too much. Retiring in 10yrs and leaving. Hold hope it changes, but I know better... It'll only change for worse.

    Damn shame.
     
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  11. Rifledriver

    Rifledriver Three Time F1 World Champ

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    I went from 8 licenses for the shop in California to 1 in Texas. And that is a resale license. Don't even need a business license. No government agencies constantly in my pocket or micro managing. Should have left many years earlier. Its beautiful in a lot of places.

    Our 328 has more miles at triple digits in the last few years than in its total prior life.
     
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  12. thorn

    thorn F1 Rookie
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    I would absolutely not advise this. By a car that's already more what you're looking for; this will be a money pit that leads nowhere advantageous.
     
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  13. Albert-LP

    Albert-LP F1 Veteran
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    This is what I think: If you don't like an injected car and you prefer the carbed one, you can sell it and buy the carbed one. That's (and by far) the cheapest way to swap to carbs and not wasting money.

    Ciao
     
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  14. mwr4440

    mwr4440 Five Time F1 World Champ
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    Brian,

    What is the easiest and or best way to achieve near 11:1?

    Thanx.
     
  15. mike996

    mike996 F1 Veteran

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    Buy a complete 11:1 small block Chevy motor for less than the price of the Ferrari pistons! :D

    Sorry ...couldn't resist. :rolleyes:
     
  16. Rifledriver

    Rifledriver Three Time F1 World Champ

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    Wossner Pistons in The Fatherland makes very nice 10.5:1 308 pistons in .5 and 1mm oversize. In your case that is probably the best way to go. You can have some made here by Wiseco or someone but Wossner is the only place I know to get quality off the shelf pistons for a 2 valve Ferrari V8.

    Their on line catalog does not seem to show them but here is an American company that shows them



    https://www.lasleeve.com/downloads/Wossner-Auto-catalog-2015.pdf
     
  17. mwr4440

    mwr4440 Five Time F1 World Champ
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    Put-In a FLAT CRANK and it just might work.
     
  18. mwr4440

    mwr4440 Five Time F1 World Champ
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    Brian,

    Thanx.

    I see no price list.

    Just as a silly wild-assed guess, what are we looking at in parts, price-wise?
     
  19. Rifledriver

    Rifledriver Three Time F1 World Champ

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    I have no idea. I have run all my prices through the shredder over the last year.
     
  20. Imatk

    Imatk Formula Junior

    May 6, 2007
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    I'm not understanding something here I guess. Is the KJet not able to add more fuel for something like a supercharger/turbo, or is it just simply easier to do it with carbs?

    OR are you just looking for the sound?

    I think (for me) if I wanted to go down this road I would imagine I'd want EFI and an ability to tune it via laptop for something like this, but maybe that's because I'm more used to that way of thinking.
     
  21. mwr4440

    mwr4440 Five Time F1 World Champ
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    Ok. Thanx.

    I'll do some more snooping.
     
  22. Rifledriver

    Rifledriver Three Time F1 World Champ

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    KJet uses air flow to meter fuel and does it mechanically. That requires very mild cams to maintain positive air flow under all conditions. Cams that mild inhibit making more HP by common methods. Methods that are available are not simple or inexpensive. Adding a supercharger is one way but not legal in some places. In my case I bored and stroked and increased compression. Again, not simple or cheap.
     
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  23. smg2

    smg2 F1 World Champ
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    Lucky bstd:p

    Rough avg retail is ~ $170~200 a hole starting point... as we know coatings, forging options, etc.. can take it right up to $300 or more..
     
  24. mike996

    mike996 F1 Veteran

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    "Is the KJet not able to add more fuel for something like a supercharger/turbo, or is it just simply easier to do it with carbs?"

    The Kjet can easily handle the fueling of an add- on supercharger at any boost level that would not require a total engine/drivetrain rebuild to handle the increased power. for example, on one of these engines that put out, say 250 HP, Five PSI of boost would produce approximately 330HP. There have been posts here in the past re the OEM Kjet providing sufficient fueling for 400+ supercharged HP AND statements that the drivetrain handled it as well with no changes! :)
     
  25. smg2

    smg2 F1 World Champ
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    Umm... That's not exactly correct. The hiccup is the WUR, for whatever reason it's a hit and miss on which one ferrari sourced. The ones with reference pressure for boost are needed, commonly found on Porsche. Sometimes they are found on a Ferrari, most times it's the std atmo one. Without it, there's a lean run problem. Otherwise, yeah it's not an issue.
     

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