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thatsnowinnebago
thatsnowinnebago UltraDork
10/19/21 10:25 p.m.

You guys like to party, right?

frenchyd
frenchyd UltimaDork
10/19/21 10:36 p.m.
secretariata (Forum Supporter) said:

In reply to frenchyd :

So the guy constantly selling the V-12 love is complaining about added complexity?  cheeky

If you think a V12 is complex, you've never taken one apart. They are simpler than a Chevy V8. If you know what you're doing you can change both camshafts in half the time  you can change a Chevy camshaft.   
     Yes the fuel injection is complex compared to modern. But so was anything from the 1970's including Chevy's. 

Stampie
Stampie MegaDork
10/20/21 6:18 a.m.

In reply to frenchyd :

Again you are ignoring how much stuff on top of the engine you have to remove to get to the camshafts.  Do you just copy and paste the same false claims over and over?

alfadriver
alfadriver MegaDork
10/20/21 7:27 a.m.

In reply to Stampie :

It's a lot easier to just ignore him.   And in the end, we should be supporting GRM's "should we do this project" question- especially since this is such a great want for fun thought.  Heck, it can even be turned into a project to find the right sound to feel faster.

maschinenbau
maschinenbau UltraDork
10/20/21 7:41 a.m.

But for real, please do this project. Very high chance I put ITB's on a 2JZ in the next year, so I'd love to work in parallel

David S. Wallens
David S. Wallens Editorial Director
10/20/21 8:39 a.m.
thatsnowinnebago said:

You guys like to party, right?

Yes, we do.

Keith Tanner
Keith Tanner MegaDork
10/20/21 10:21 a.m.

Must just be me, but it seems that a V12 should be approximately 50% more complicated than a V8 based on parts count. 

noddaz
noddaz UberDork
10/20/21 11:44 a.m.

David S. Wallens
David S. Wallens Editorial Director
10/20/21 11:57 a.m.

In reply to noddaz :

Yup, the Jenvey kit looks very cool. 

JoeTR6
JoeTR6 Dork
10/20/21 11:57 a.m.

Yes.  Yes it does.

MadScientistMatt
MadScientistMatt UltimaDork
10/20/21 12:42 p.m.

The last time we dynoed ITBs on a 1.6, the car only picked up less than 10 hp at the wheels. One wag on MiataTurbo.net's reaction was "Yes, they look and sound cool, but for $2000, I can buy a pimp suit and a guitar, and look and sound cooler."

Perhaps a good question to explore would be what sort of engine can really use these ITBs to their full potential. When would they make sense, and when would the money better go towards a turbo kit?

captdownshift (Forum Supporter)
captdownshift (Forum Supporter) MegaDork
10/20/21 1:01 p.m.

I think 3 pages of discussion in less than 2 days means that it has the interest of the people and thusly from an article standpoint, it should be done. 

 

 

*Please note that I'm not a publisher, nor an editor nor do I pretend to be one on the internet, so the feelings expressed or merely one man's highly questionable opinion* 

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
10/20/21 1:44 p.m.
MadScientistMatt said:

Perhaps a good question to explore would be what sort of engine can really use these ITBs to their full potential. When would they make sense, and when would the money better go towards a turbo kit?

Start with the kind that "can't" use a turbo kit (rules, strong personal preference, etc) otherwise boost it and call it a day.

z31maniac
z31maniac MegaDork
10/20/21 2:55 p.m.
alfadriver said:

In reply to Stampie :

It's a lot easier to just ignore him.   And in the end, we should be supporting GRM's "should we do this project" question- especially since this is such a great want for fun thought.  Heck, it can even be turned into a project to find the right sound to feel faster.

I know I'm big contributor to the "shut up frenchy" stuff. And I should ignore him, but I don't like seeing blatantly false, misleading, or incorrect misinformation being shared on a forum that is known for having a good signal-to-noise ratio. 

David S. Wallens
David S. Wallens Editorial Director
10/20/21 4:38 p.m.

In reply to JoeTR6 :

So, how has the experience with the company been? 

JoeTR6
JoeTR6 Dork
10/20/21 5:11 p.m.
David S. Wallens said:

In reply to JoeTR6 :

So, how has the experience with the company been? 

I bought my throttles (DCOE-style) through a US distributor that I wouldn't recommend.  But then again, Jenvey also no longer does so.   So I do not have any experience dealing with Jenvey directly, and can only speak about the product.  I'm very satisfied.  The quality compares well with TWM/Borla (with another set of TR6 throttles).  My only issue was with some machining swarf keeping one of the fuel rail o-rings from seating, and that was easily removed once identified.  So far, they are working great.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/20/21 5:13 p.m.
Junghole said:

Does the hp gain outweigh the torque loss? 

Usually, ITBs make the low load/low speed areas much more crisp, because there is a lot less reversion.  Vacuum dies quickly in the short space between the throttle plate and intake valves, so exhaust tends not to backfeed into the intake on intake valve opening.

It was definitely the best thing I did to the RX-7.

 

Peak power will actually be higher with a well sorted plenum manifold, but the overall powerband, and part throttle drivability, tend to be better with ITB.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/20/21 5:21 p.m.
MadScientistMatt said:

The last time we dynoed ITBs on a 1.6, the car only picked up less than 10 hp at the wheels. One wag on MiataTurbo.net's reaction was "Yes, they look and sound cool, but for $2000, I can buy a pimp suit and a guitar, and look and sound cooler."

Perhaps a good question to explore would be what sort of engine can really use these ITBs to their full potential. When would they make sense, and when would the money better go towards a turbo kit?

Big cams installed with a tight lobe center will love ITBs.  Or vice-versa?

David S. Wallens
David S. Wallens Editorial Director
10/20/21 5:24 p.m.

In reply to JoeTR6 :

Thanks for the feedback. I stopped by the Jenvey booth at SEMA or PRI, but this was years ago. Color me intrigued about the whole thing. 

Keith Tanner
Keith Tanner MegaDork
10/20/21 5:31 p.m.

Boy, if only there was a SEMA show in a few weeks :)

At one point I had a turbo 1.6 and a tricked out 2.0 Miata in the garage. Peak power was pretty darn similar, investment on the 2.0 was probably 4-5x as much. You don't do it for the bulk hp/$ ratio, that's for sure. But that 2.0 was a very, very fun engine. And there clearly is interest. 

David S. Wallens
David S. Wallens Editorial Director
10/20/21 6:03 p.m.

In reply to Keith Tanner :

And if only I knew someone who's already been down this road before. laugh

thatsnowinnebago
thatsnowinnebago UltraDork
10/20/21 6:09 p.m.
David S. Wallens said:
thatsnowinnebago said:

You guys like to party, right?

Yes, we do.

Sounds like you know what to do then. 

mke
mke Dork
10/22/21 8:55 a.m.

Come on in, the water's fine!

It looks like all the issues have been touched on.   There is no 1 thing that makes ITBs hard to get right, but there are a lot of little things ...how to get a good MAP signal (or how to get alpha-n working well at low power), how to get IAC working right, how to get and keep them sync'd, how to install an air filter, how to get it to come off idle smoothly....you just have a lot more opportunities to get something not quite right and have a frustrating experience.   

All that said, its not that hard, especially on the 4 cyl where there is only 1 bank to deal with.  Every sport bike made is setup this way these days....because it makes the most HP which means there is no other option right?  

I'll add this, unlike with carbs there is very little downside to a TB that is bigger than needed.  The bigger the TB the harder is it to get a smooth off idle transition and it theory it could cost HP because there is more air mass in the intake track to accelerate so velocity should in theory decreases.  In practice though the stuff I've tried or seen tried what happens is the hp goes up as TB size goes up until a bigger TB no longer helps....I've never seen the hp start coming back down, not to say it couldn't, but I've not seen it.  The easiest way to pick the right size TB is when the head is still on the flowbench....you up size the TB until the flow stops going up and that result will match the dyno test result without needing to pay for dyno time or burn your hands swapping hot parts.

When I was picking TBs for the frankenferrari I tried a couple sport bike options, a couple more junkyard options, its only 1 cylinder so any TB will do, it doesn't have to be a viable real setup, you're just checking sizing then you go shopping for parts that will work on a real engine.

A 150hp 4 cyl is a large sport bike and those TB sets are pretty cheap on ebay if you have the ability to get them on the engine.  

I did this intake conversion for a guy who then added sportbike TBs.  It's a stock manifold with the plenum sawed off and adapters welded on.   It used the OEM injectors and fuel rails as well. Then you can see the spacers he added between them to get the spacing to match the new engine cylonder spacing.  This was a 12 so I think he needed 4 sets to get the right combination of inner and outer TBs but on a 4cyl you just need 1 set...$100 + $20 of aluminum tubing and maybe 8-20 hours total work....very inexpensive conversion, but just because its inexpensive doesn't mean it can't look and work well.

So I'd say the more throttlebodies the better :)

 

Driven5
Driven5 UltraDork
10/22/21 12:39 p.m.
z31maniac said:

I know I'm big contributor to the "shut up frenchy" stuff. And I should ignore him, but I don't like seeing blatantly false, misleading, or incorrect misinformation being shared on a forum that is known for having a good signal-to-noise ratio. 

While using noise to cancel noise may work in the audio world, that part doesn't actually translate into metaphoric usage. It just makes the signal-to-noise ratio even worse.

 

Speaking of noise... I think mke may be on to something!

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/23/21 6:42 a.m.
mke said:

I'll add this, unlike with carbs there is very little downside to a TB that is bigger than needed.  The bigger the TB the harder is it to get a smooth off idle transition and it theory it could cost HP because there is more air mass in the intake track to accelerate so velocity should in theory decreases.  In practice though the stuff I've tried or seen tried what happens is the hp goes up as TB size goes up until a bigger TB no longer helps....I've never seen the hp start coming back down, not to say it couldn't, but I've not seen it. 

The part where my brain exploded was when I was reading about a dogbone Escort in California that had an Esslinger 3.3l "Lima" based engine, making about 400hp.  That is still an eight valve head.  He described the intake as having "only" 55mm throttle bodies. 

That is, 55mm per cylinder.

Yoicks!

He also described walking away from YBB (Sierra/Escort Cossie) swapped Escorts at Laguna Seca, with half the valves and none of the turbos.

 

Teh RX-7 has 4x42mm throttle plates, which is actually restrictive per datalogs.  Ignoring the 1.3l BS, each chamber is like a 2.6l four's chamber, each chamber pulls from two throttle plates, so two 42mm throttle plates per "cylinder" is too small.  Have a proper DCOE manifold on the shelf, was considering 45mm throttles, but maybe 50mm would be better.

Not that it needs all that much top end charge, but once you get locked into a serious horsepower collection, the tendency is to push it as far as you can.

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