peter mc Posted May 27, 2013 Share Posted May 27, 2013 The 5% that you feel is in the drive from idle to 3000 rpm , the EFI starts better and idles better if its done right , and drives better around town if you have a real cam , but it takes some time to get the tune spot on , its never cheep .With a good set of carbs it will be 1/4 the cost if you do it right from the start , i think you should drive both and make a decision , I'm shore i could get two cars with the same spec engines one with EFI and one with 45 Weber's so you can try them and then spend your cash Quote Link to comment Share on other sites More sharing options...
luvemfast Posted May 27, 2013 Share Posted May 27, 2013 My point being. Break it down to dollars. You'll spend $4k on itb's, then $2.5k on ECU. Then tuning a map. My mate has spent thousands on the dyno, autronic running itb's and spark on his V6 Renault Alpine. Triple Mikuni's $2.5k and tune $700. Got an extra $5k or so in pocket to get head and exhaust flowing better. I know which one would go better! WOT comes down to physics. Air and fuel delivery will be ball park when set up properly. As far as running cold. I've not started my Z since the Nationals and know I can go out to the garage and she'll fire straight up. Quote Link to comment Share on other sites More sharing options...
Zedric Posted May 27, 2013 Author Share Posted May 27, 2013 The 5% that you feel is in the drive from idle to 3000 rpm , the EFI starts better and idles better if its done right , and drives better around town if you have a real cam , but it takes some time to get the tune spot on , its never cheep .With a good set of carbs it will be 1/4 the cost if you do it right from the start , i think you should drive both and make a decision , I'm shore i could get two cars with the same spec engines one with EFI and one with 45 Weber's so you can try them and then spend your cash @ $690 per carb and $700 for a decent manifold + dyno time how could it be 1/4 the cost. I know ITB's and a state of the art ECU + ancillaries will be much more expensive, but 4X? I've heard so many times on this forum that smooth idle, less emissions and such aren't worth the extra $, I thought that the most power through the greatest efficiency and lowest emissions with the smoothest operation was the goal of anyone serious about the internal combustion engine. I remember arguing with someone about forced induction and remember them saying " it's only for race cars that don't care about fuel economy" so that's why the diesel electric trains that operate up north are both turbo charged and super charged, because they don't care about economy? I'm a Le Mans fanatic and you can bet that economy wins races. Anyone that knows anything about engines should know that the higher the compression ratio the better the economy and power for a given amount of fuel, that's where precise fuel delivery comes in, detonation kills engines. When I was a kid a 10:1 comp ratio was considered high, now 10:1 is inefficient by most OEM standards as fuel metering as well as precise ignition timing with a good Knock sensor just in case allows higher compression ratios safely. Quote Link to comment Share on other sites More sharing options...
peter mc Posted May 27, 2013 Share Posted May 27, 2013 I'm fully up for injection , love it and gives great results , but I'm really into the carbs for a classic car feel and look .its so easy to just fit a new LS or Rb and have them run smooth , but that's not what people fall in love with, driving a classic with the sound and smell and feel is just so cool I'm thinking if you really want a smooth car and great economy and good power best buy a new car , L motors were never built for clean burning and smooth running , no matter how hard you tune , most want a cam that feels and sounds strong , never good for economy , i will let you drive a good injected 320hp car and a 310hp carbed car and we will go thou all the costs and then make a decision , i love both but the cost of the injection is hard for some Quote Link to comment Share on other sites More sharing options...
Zedric Posted May 27, 2013 Author Share Posted May 27, 2013 I'm fully up for injection , love it and gives great results , but I'm really into the carbs for a classic car feel and look .its so easy to just fit a new LS or Rb and have them run smooth , but that's not what people fall in love with, driving a classic with the sound and smell and feel is just so cool I'm thinking if you really want a smooth car and great economy and good power best buy a new car , L motors were never built for clean burning and smooth running , no matter how hard you tune , most want a cam that feels and sounds strong , never good for economy , i will let you drive a good injected 320hp car and a 310hp carbed car and we will go thou all the costs and then make a decision , i love both but the cost of the injection is hard for some I have to disagree on the smooth running L motor thing. You might be too used to massive cams. I can remember 18 years ago I used to rock up to friends houses and they would freak out thinking they were being raided by the police because the only cars that sounded as smooth as mine were brand new police cars. I would love to even see these cars that you have mentioned, you name the time and place and I will be there, either way I'm going to spend big $, because there is no other way to achieve what I want. Quote Link to comment Share on other sites More sharing options...
luvemfast Posted May 27, 2013 Share Posted May 27, 2013 I'd like to see these cars too! I can feel a meet coming on Quote Link to comment Share on other sites More sharing options...
pauly_adams Posted May 28, 2013 Share Posted May 28, 2013 but when you look at people like myself with a turbo, ITB is much more tunable Quote Link to comment Share on other sites More sharing options...
luvemfast Posted May 28, 2013 Share Posted May 28, 2013 but when you look at people like myself with a turbo, ITB is much more tunable Would you really go ITB turbo? Quote Link to comment Share on other sites More sharing options...
pauly_adams Posted May 28, 2013 Share Posted May 28, 2013 one word, yes Quote Link to comment Share on other sites More sharing options...
luvemfast Posted May 28, 2013 Share Posted May 28, 2013 One other word......... Why? What's the advantage? Quote Link to comment Share on other sites More sharing options...
pauly_adams Posted May 28, 2013 Share Posted May 28, 2013 flow, its custom made manifold might be able to use 70mm throttle body or run 6x40mm throttles with my ported head it will boggie and give good low down torque Quote Link to comment Share on other sites More sharing options...
Zedric Posted May 28, 2013 Author Share Posted May 28, 2013 One other word......... Why? What's the advantage? GTR Skyline RB26DETT is twin turbo but has ITB's, SR20DET with quad TB's, it's all about air flow. The better you can evenly distribute air flow to the cylinders the more accurately you can control A/F to each cylinder. Equal length runners on an intake manifold work the best, but with turbo systems you should have a plenum the size of the volumetric efficiency of the engine at the very least. If you have one intake at one end of a manifold that has to feed six cylinders, how could you expect it to feed all cylinders evenly? It just wont. If you have a large enough plenum to store that above atmospheric pressure, it will be even across the six butterfly's and when you crack the throttle you will have an even flow of air to all cylinders. No setup is perfect, that's why those who are seeking 1000hp ditch the ITB's and just use a single very large TB with a single very large turbo. And you can bet that driveability and low emissions are the last thing on their minds. Quote Link to comment Share on other sites More sharing options...
Vic Dyno Hire Posted May 28, 2013 Share Posted May 28, 2013 Having one throttle plate per cyl doesn't guarantee even distribution to the cylinders in a turbo application. This is still primarily the plenums job, especially at larger throttle openings. Quote Link to comment Share on other sites More sharing options...
pauly_adams Posted May 28, 2013 Share Posted May 28, 2013 there would still need to be a good intake, but ITB is a lot more efficient then a L28 manifold or even many custom ones, the sound is also a bonus Quote Link to comment Share on other sites More sharing options...
luvemfast Posted May 28, 2013 Share Posted May 28, 2013 GTR Skyline RB26DETT is twin turbo but has ITB's, SR20DET with quad TB's, it's all about air flow. Yes. And are twin cam cross flow heads. Which L series are not! Zedric, you seem to want to go ITB's. So just do it! Quote Link to comment Share on other sites More sharing options...
zedevan Posted May 28, 2013 Share Posted May 28, 2013 the sound is also a bonus Wouldn't the sound largely be lost from the turbo effectively blocking it? I personally can't identify a gtr vs a gts-t by its intake noise - but they are typically running hectic exhausts Quote Link to comment Share on other sites More sharing options...
Zedric Posted May 29, 2013 Author Share Posted May 29, 2013 Yes. And are twin cam cross flow heads. Which L series are not! Zedric, you seem to want to go ITB's. So just do it! I agree with you about that for sure. As far as "just do it" goes, when I started this thread I was after some info on different ITB brands and setups. I didn't want to spend a heap of money and later wish I had bought something else. Quote Link to comment Share on other sites More sharing options...
luvemfast Posted May 29, 2013 Share Posted May 29, 2013 when I started this thread I was after some info on different ITB brands and setups. Too true Quote Link to comment Share on other sites More sharing options...
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