# 16v ITB intake runner length. How long are yours?



## NTRabbit (Mar 28, 2001)

I'm using GSXR throttle bodies on my 16v engine (running 276 cams), and I'm trying to decide how long to make my intake runners. I am about to fab up the intake manifold to adapt to the ITB's, and I'm going to keep it fairly short. I was then planning on running some tubes down toward my grill where they would be capped off with some velocity stacks. The total runner length would then be about 12". 
I want to get some super charger effect from the long runners, but I'm affraid that I am going to kill what little low end power I have left by making them long. This car is only for fun, and is not a daily driver. Anyone out there have experience with trying different runner lengths? 
Here is a rough drawing of what I mean. The picture is drawn as if you are looking at the side of the engine bay from the timing belt.








Also, I am running a custom radiator that won't block the front grill area at all infront of the cylinder head. 

_Modified by NTRabbit at 3:24 PM 2-5-2007_


_Modified by NTRabbit at 3:29 PM 2-5-2007_


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## wobvintage3 (Jun 10, 2005)

*Re: 16v ITB intake runner length. How long are yours? (NTRabbit)*

Nick.... I think you would be fine running something within the 12-16" range.. 
According to this calculator http://www.velocity-of-sound.c...3.htm intake valve to bell mouth should be around 14". 
That is if I am using it right that is...
? Are you running the same radiator as Matt is on his bunny?
Second ?, when are you coming over to install my ms


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## NTRabbit (Mar 28, 2001)

*Re: 16v ITB intake runner length. How long are yours? (wobvintage3)*

haha, yeah, it is the Full-Race radiator. I ordered it yesterday. Unfortunately, I had to pay full price for a new one because I couldn't find any others. $330. 
You should call Matt about this weekend. I'm sure we will be over at his place tuning his car some more. We worked on it for a couple hours on Saturday, and got his base fuel map smoothed out a little. It is very driveable now, just not fine tuned in any way. It is starting to run really well though. 
Thanks for the link about the intake runners. It is actually the website that I plan to buy my bell mouths from, but I didn't see that calculator before. 


_Modified by NTRabbit at 7:22 AM 2-6-2007_


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## NTRabbit (Mar 28, 2001)

*Re: 16v ITB intake runner length. How long are yours? (wobvintage3)*


_Quote, originally posted by *wobvintage3* »_
According to this calculator http://www.velocity-of-sound.c...3.htm intake valve to bell mouth should be around 14". 


What is your "number of induction waves" supposed to be?


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## wobvintage3 (Jun 10, 2005)

*Re: 16v ITB intake runner length. How long are yours? (NTRabbit)*

Shoot, I was hoping you sourced something a little cheaper than the full race







I might have found another but it is 14.5 X 15.5 for $ 150







. It would fit in my mk2 (tight), but probably wouldnt work in a mk1.
I will be attempting to finish up the wiring on mine sat., but will try to stop by.

According to them it should be 3 
"This calculator will determine the most efficient overall length of the intake runners to optimize the intake system for the third induction wave (the first and second waves are usually too long for most practical applications - NASCAR engines use the third wave too)" 
That is if I am interpreting this correctly...

I have another place to get horns, also aus. but about $50 cheaper than vos. Only problem is they dont accept paypal. I will post the link later


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## wobvintage3 (Jun 10, 2005)

*Re: 16v ITB intake runner length. How long are yours? (wobvintage3)*

http://www.elettra.com.au/spinnings/new_page_1.htm
The guy quoted me $87 shipped for 50x130's...


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## NTRabbit (Mar 28, 2001)

*Re: 16v ITB intake runner length. How long are yours? (wobvintage3)*

Sweet. The ones I was looking at were 50mmx120mm, and they were $120 for four of them, before shipping. Thanks.


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