Hello everyone! I've been lurking for a while now and decided to make an account to bring my build to light and ask for some advice. I am building a turbo charged Yamaha Raptor 700 for drag racing for the fun of riding but also to learn the advanced theories and science behind turbocharged systems, suspension setup, and engine building in general. This is all happening along side being in college in Indiana so progress is slow as i live in south central MI and cant be home every weekend but i'm trying to make sure everything is built to the best it can be and not cutting corners on this build.

What I have now:
2006 raptor 700, engine is a 686cc single cylinder that is completely stock except for a 10:1 compression piston (as opposes to the 9.5:1 ratio in the stock motor), a set of ARP head bolts, and the head off of a 2015 raptor. the reason for the head swap was due to the fact that there were a few internal changes but mostly for the fact that it has a single large exhaust port instead of 2 smaller ports which make it much easier to build a header.

The bike started off with a bolt on turbo kit with a stock motor and made reasonable power at ~83 hp, as opposed to the stock 33 hp, at 12 lbs of boost. I decided that I wanted to push the boost up more and begin to work towards more power so I upgraded the fuel system with a walbro 155 in tank fuel pump and a return style fuel system to allow me to run E-85. After turning up the boost a bit more and re tuning, i made ~ 95 hp and rode the quad like that for a while. I then decided that I wanted to really push the motor and attempt to set a record as to the maximum power i can make on a stock bore, stock stroke (SS/SB) motor and that is what im in the process of currently. I talked to a friend of a friend who had built his own turbo system for a raptor and made good power doing so on a stock motor and got his design to follow for what i have built currently. the only problem with follow this to the T is his goal VS mine. His build was only ever supposed to work for a completely stock motor and be something fun to ride. I want to hopefully make record setting power and know that i need to make changes to his design to get where i want to be or at least as close as possible.

I'm wanting to learn how to verify the design info i was given (stuff like header diameter and length, charge tube diameter, plenum size, correctly sized turbine and compressor setups to name a few things) and also at least get a poke in the right direction as to later modifications (head porting, compression ratios, etc) to get to the power level i'm wanting to attain. And through learning how to verify all this info, learn more about the in depth science involved in turbocharged applications as this whole project is really just a learning experience for me.

Currently, the quad is down in Indy getting a custom wiring harness built for it and a Fuel Tech 450 stand alone ECU so I can have full control and data log to my hearts content. Ive taken photos here and there that i can provide to sort of give a visual of what i'm trying to build here and can also provide any of the specs of things I have already built.

My goal:
As close to 150 hp as possible if not more if possible on a SS/SB motor and learn the correct way to get there to apply to later projects.

First, id like to verify some info ive been told and see what you all think on how well it was implimented here. The equation I have found for plenum size is: max RPM x cylinder size / # of cylinders so in my case with a 686cc engine revving to ~8800 RPM it would be: 41.86 in^2 x 8.8/1 = 368.4 in^2 is the theoretical volume wanted and with how the plenum was mounted and the space we had, we got the volume to right at 343 in^2 so we were close. I was also told that the charge tube and the plenum should be separated by a turn and not be blended into one long tube so i built the charge tube into the upper half of the cylindrical plenum so the air will swirl as it enters the plenum and keep at least some of its velocity before being pulled into the engine. this need of separation of the charge tube and plenum is one thing i dont fully understand but the way i understand it is during a normal engine cycle, right as the intake valve closes, the high velocity air moving into the cylinder is stopped by said valve creating a shock wave that bounces back down the intake runner and into the plenum and as it hits the back wall of the plenum, it will bounce back and send a higher pressure wave of air into the intake if the motor is at the correct RPM for the shock wave reverberation to catch the intake valve open and stuff the extra air into the cylinder. this separation of the charge tube and the plenum is to make sure that shock wave doesnt shoot all the way back up to my intercooler and break that shock wave but correct me if im wrong or if i am over simplifying it.

the second thing i would like help understanding is the reasoning behind the turbo being placed 14" away from the header as i was told is best for the turbo and motor. i assume it has to do with the expansion of gasses and flame lengths to get the highest efficiency out of the hot side of the turbo. Can someone possibly explain or direct me to where i can learn how to measure and calculate what i need to arrive at this determination? maybe at least a semi basic explanation will clear some things up about that since ill be honest and say that i dont understand how he got this length of header.

I have many more questions but i will leave it at that for now as i dont want to write a full book and i doubt any of you, especially Mr. Vaught, wants or has the time to read said book.

Thanks in advance everyone!

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In my somewhat limited experience with single jug turbo engines, the plenum volume was really critical to getting the engine to work coming into boost. I attributed it to the large pressure swing in the plenum due to the single large cylinder but never really dug into it deeper. i just know I needed to run a much larger plenum area then made sense to me at first glance.

 

Would it matter as much taking into consideration that it is EFI? Richard Holdener tested a HUGE plenum made from a beer keg on a LS intake and it made absolutely no difference.

 

Well like fastspec said, the need for a large plenum is only needed for a single cylinder engine. it has to do with the fact that the turbo is only getting an exhaust pulse every 720 degree of crank rotation so the engine needs a large mass of charged air to pull from when the intake valves open

 

Ah ok. I was thinking about it from a "signal" point of view as in with a carb. Plenum volume affects performance on a carburetor V8, but has no effect with EFI.

 

I have been involved with several Twin Turbo EFI V-8 Race projects where the Plenum Volume did make a difference and in most cases the Volume was approximately twice the volume of the engine displacement.
So I would agree with Sparky122sparks that, with a single bore/piston engine, the plenum volume is not something to be ignored.

Tom Vaught

 

Tom, would you happen to have any insight as to if the need for separation of the charge tube and plenum is necessary and if so why?

 

Tom, would you happen to have any insight as to if the need for separation of the charge tube and the plenum/ intake runner is needed and if so why?

 

Here is the Richard Holdener Plenum Article. https://www.hotrod.com/articles/introducing-kegalodon-shark-week-made-us-do-it/ Tom V.

Bad Medicine Racing said: ↑
Would it matter as much taking into consideration that it is EFI? Richard Holdener tested a HUGE plenum made from a beer keg on a LS intake and it made absolutely no difference.

If you look at the info Richard H. posted, it made a large difference in power below 4000 rpm.
Last time I looked, except for a pure Street Racer/Drag Car, every normal engine has to go thru that idle to 4000 rpm band before it can get to 7000 rpm.

Some people say that a large plenum engine acts like a individual runner mechanical fuel injected engine in a large room of air. The runners and the injector are setting the power. The room just has plenty of air volume for the engines need to make power.
But if you do not have enough plenum volume then the engine plenum becomes a restriction for making a large power number unless you have very large throttle bodies on each runner.

We did a test program on a SB Chevy Engine at Holley Carburetor many years ago, with a special individual runner intake and TWO of the special 2400 cfm Holley 4600 Dominator Carbs. (They made TEN CARBS TOTAL.) Each throttle bore flowed 600 cfm.
8 cylinders you get 4800 cfm needed for the engine to run high rpm with individual runners as each cylinder had to move all of the air needed at high rpm thru that one Throttle Blade which was 2.75" in diameter. With a decent Plenum below the throttle blades, you could feed the same engine with 1150 cfm Dominators. 1/4th the airflow needed.

So the plenum in needed and the size DOES make a difference.

Tom V.

 

Another consideration when going efi was the erratic map signal. It took a fair amount of time to find the map sampling angles that worked with the ecu.

 

That confirms my knowledge of the need for plenum volume and it seems especially compounded in my situation with a single cylinder application. I read up on the Helmholtz resonance and the other forms of charge filling and based off of what ive read, that is part of the need for a 90 degree separation between the plenum and the charge tube but i will do more research and see what i can find.

My next major question would be on the topic of header length and size and how the numbers i was given were reached. I would assume it pertains to the EGT and how that gas expands over time, with the turbo placed at a point where the gasses are at possibly the best volume to velocity ratio to spool the turbo efficiently. let me know if im completely off base here.

 

This V-8 Pontiac Engine (approximately 440 inches) uses a single 118mm Turbo and smaller primary tubing to the single turbo to get the turbo to spool quickly. The idea is a higher temp/higher velocity exhaust flow to the split scroll turbine housing to make the turbo more responsive. No inter-cooler on this engine either. Methanol fuel is used with 16 160 lb injectors. The intake uses a simple elbow into the intake manifold plenum.

In this case the intake design has been dialed in for the size of the turbo flow. The heads are wide port heads.

Tom V.

 

that sure is a beautiful picture tom and good info on the car. So my brother is big into diesel truck pulling here in michigan and he has a friend who does a lot of turbo tuning for that area and he has shown some interest in the project so it seems he will be helping me to understand the science behind picking the correct compressor/turbine combination that is close to what i need then will be helping me tune the compressor map with a custom wheel. He has produced some crazy large numbers from correctly built turbos on diesel trucks so i think this will produce good results and hopefully i will learn on the way.

 

Where in Michigan are you located?
I know that Steve Morris is in Muskegon Michigan and has made some large power numbers over the years.
Another Turbo Expert a bit farther south is Tom Earhart (who is south of Grand Rapids).
He was making enough power with his small engine stuff to be elected to the Michigan Motorsports Hall of Fame.
https://mmshof.org/index.php/inductees/inductees/76-tom-earhart

He is still making power from small cubic engines today.

Tom Vaught

 

Tom, i am located in south central MI. Jonesville, between coldwater and jackson on US-12. That is interesting to hear and i will have to look him up and get into contact. Thanks!

 

As a moderator I can delete the post for you.
Tom Earhart would be the guy I would talk to.
I may be able to get his contact info and send it to you if he is still doing boost work.
He had a flow bench, engine dyno, and welding and machine shop capabilities as a private individual.

I will PM you if I get his info.

Tom Vaught

 

Thanks for the delete and if you do get his info, I would love to talk to him, see if he has an interest in what im doing and if nothing else, bounce some ideas off of him.

 

Tom Earhart
Earhart Engineering
10571 Gun Lake Rd, Middleville, MI

 

My next main question would be header length. Ive heard people talking about pipemax but am unsure if that will work for turbocharged applications. Are there any programs built for turbocharged applications or is there any way i can do the calculations by hand?

 

Pipe diameter affects turbo response. Long Pipes affect turbo response.
Large collectors before Turbochargers affect turbo response.

Turbo Guys racing heavy bodies have gone 6.80s in the quarter with 118 mm single turbos with small exhaust systems.
Big exhaust systems look impressive but then you need band aids like dropping cylinders to have the charge burn in the large pipes to get the things to spool properly.

So throwing on a big set of pipes and collectors is not the answer for most drag type events unless you are running 14-71 superchargers and Zoomies. Turbos need heat and charge energy to spool properly and that required spending the time to OPTIMISE the EXHAUST before the Turbo(s) vs just throwing something together.

JMO

Tom V.