jspinn13

alright guys, i am currently building an n/a h2b setup that i am looking for get about 280-300+whp out of.

so far i have
RLZ 350cfm cnc ported head with ferrea 6000 +1mm valves, complete supertech valvetrain with 87lb springs, ddtech reaper 3 lobe cams

darton flanged sleeved block 95mm h23 crank, h22 lenght rods, will be using arias 13.5:1 compression pistons in either 89 or 90mm bore (not sure what the flanged sleeves will handle bore wise)

currently have a set of twm 52mm itb's that i got only because they were a steal, what i am wondering is are they too small? is there a larger size that i should go with that isnt overkill? ive read that they will flow 360cfm off the shelf can anyone confirm this? i know oversizing can kill power just as much as undersizing.

thanks in advance for the info!

TracerAcer2.2L

Why not call TWM and ask? I doubt anyone on here will have the cfm that TWM ITB's flow off the top of their head, but maybe.

What size TB did you use for your H22 turbo build?

GhostAccord

There are calculations available to give you an idea of what will work for you.

Here is one that will give you a basic number, Calculate Throttle Blade Diameter

There are others out there, remember that the more information you put into the calculation the better. This is just a crude one to get you started.

PipeMax is what I have used in the past with good results.

jspinn13

ok so according to the site you posted i should have a throttle blade diameter of 8.77 inches, which im guessing you divide by 4 for the 4 individual throttles, so 55.6(56)mm would be ideal, but i feel like there are many more factors that come into play, such as throttle distance from the valve, and length of the trumpets.. does anyone else have any information? any cfm numbers or experience they can give?

GhostAccord

If you clicked on the link that I posted it will calculate for 4 x individual throttles..... however you came up with close to the same figure, I got 54.65mm (55mm) for your displacement. Did you input your engines CC's as your CID?

That is why I said the more information you input to a formula/calculator the closer your results will be for your application. That was just one I found with a 2 second Google search.... very easy to find!

The software I use requires that you fill in 24 fields in order for it to calculate CFM and throttle plate diameter. It will also determine runner length/volume for a given engine setup.

Where you are looking for freeware, most times these simple online calculators aren't quite as precise/accurate.

crazes

I think that will probably be to small for your setup of air flow. I would look at least 56mm. I would also look at creating some sort of airbox for your ITBS. One of the biggest drawbacks of having a H is the lack of direct ram air into the heads. Granted this is all dependent on if this car is for drag racing. If your are using this a daily 54 would be a great starting point.

unusual71

I have a very similar setup. are these the k24 13.5:1 arias pistons? they suit the hseries combustion chamber well IMO. I went with 88mm bore. I only put like 2000 miles on it but they look good so far. I only tore the motor apart because I blueprinted, built and tuned it all myself. I will freshen it up and adjust my main clearances slightly for this year.

I am interested to see how the DDTech cams will work for you. they are on my list for 2015. I ran junk2 Pro2s this year which was fine.

You are right that the distance of the throttle plate to the valve effects the setup. The other important aspects are overall runner length, runner volume and how the runner transitions from round to intake port shaped. The last one obviously depends on the head as well which creates a large challenge. the unity with which all of the components work together is what separates the cookie cutter builds from the big guys. You will probably be able to hit your goal but you dont mention how you intend to use the engine when you're finished.

for what it's worth i put together a prototype intake based off of stock 55mm throttle bodies, which is the best size for about 300 whp and a good powerband for a streetable car. I am working on a second prototype using my own casting. If you can wait a couple of months I will have a couple extras which I will make available to help determine feasibility of doing a batch of these through my work. The casting is designed to support 55-65 mm throttle plates. I will have a casting on my desk in a few weeks, message me for more details.

here is a picture of the first h-series prototype using stock d16 throttle bodies (cut, welded and epoxied), looking down the runner at a stock port.

TracerAcer2.2L

I highly agree with crazes, I have been a proponent of plenum ITB's for some time. I feel most of the Honda world lags behind in the ITB department concerning this.

Unusual, that's pretty sweet! It's cool that you have access to the tools to create the castings. Have you considered making the throttle plates "verticle"? I've never seen any hard evidence that it is better but, all the ITB manufacurers are doin it

GhostAccord

I'm not a big fan of the vertical plates on Honda's. I'm not really sure why. Other than some of the differential pressure/flow diagrams that I have seen throw me off. Also the fact that they run perpendicular with the valve face.

It seems as though the throttles for Honda cars are mostly vertical or perpendicular with the valves as you mention. However, a lot of the throttles for production ITB engines and high performance sport bikes, V8's, F1 and exotics are horizontal or parallel with the valve face.

For example, take a look at the Kinsler FI manifolds. If you look at the ITBs that they make. There are a lot of them with the plates opening parallel with the intake valves, not perpendicular. With the exception of the Honda ones and a few others????? Maybe it's a 4 cylinder thing??????

TracerAcer2.2L

Hmm interesting....I remember reading on some thread that Bisi tested it and it flowed better or something....but that was Bisi so who knows

unusual71

I would imagine it would flow better in the way that the flowbench displays a higher numerical value when tested but like Ghost mentioned, there are a LOT of examples to study. I looked closely at I4 motorcycle cylinder heads for inspiration in designing the intake. i have an 07 cbr600rr which i have gotten intimate with to say least.

My take on it was this. for driveability on the street, I feel that positioning the fuel injector right behind the throttle with the blade in that orientation and far away from head is the only way to go. the well designed systems seem to be going this route but i think it makes the system sensitive to the runner volume and cam timing. The Honda head is a "tumble" flow configuration so the intake should support that, hopefully my reasoning and calculations pay off.

Some type of plenum or air box is a must. Ram air is better. people often claim that the K is better than the H because the head flow is in a more efficient direction but with the right hood scoop and air box you really only need to force the air to make one major direction change so the difference is almost negligible.

GhostAccord

I too took my examples from the bike world with regards to induction and exhaust systems.

Here is the set that I had originally built for my 2.4L F22 Build. it is now being put on a 2.0L Ford ZETEC engine.




I kept the throttle spacing on this one so that I could use the stock GSX-R air box. I realize that is not the optimal, and keeping the runners straight would have been better. However, this is a budget build and I do not want to separate the throttles and have to build a custom throttle bracket and air box for this build.


The 54mm Ducati 999r throttles, that are going onto my Accord, are spaced properly and will require a custom air box.




I have the air box design drawn up in CAD, it's now down to making it..... going to start with a fiberglass plenum and see how that works.

Using the 54mm diameter 999r throttles for the 89mm x 95mm F22 engine is based on flow calculations and valve train specs. This build is not as high compression or RPM as the OP is.

TracerAcer2.2L

Ducati top feed! Sick! Do those come in 56/55mm by any chance?

Question for Ghost or unusual. It is well known that top feed injection is ultimate when it comes to making top end power (as far as ITB's go). I always wondered though, wouldn't this injector positioning greatly impede airflow and increase turbulence? My only conclusion is that the vacuum must pull air from mostly around the bellmouth, rather than just through the middle. Of course this idea is based on no testing whatsoever, that's why I'm asking

jspinn13

no since i am using the h23 crank and h22 rods i will be using custom arias pistons, my overall compression in the motor with a non milled head and stock thickness ehadgasket shouldbe close to 18:1+

car will bea straight track car, i am only using the 3 lobe cams rather than 1 or 2 lobe killers because i plan on maybe driving the car to a local meet rarely or even driving to the track if i have to. other than that it will be a strict track car

please keep me informed on your castings. i am very interested.

jspinn13

i am doing an air box with any itb setup i do for sure.

jspinn13

what would you guys say abot porting the 52mm's? worth doing? will it increase overall flow and potential power?

in this post pocketrocketsracing claims stock twm 52mm's flow over 340cfm

https://honda-tech.com/all-motor-nat...-52mm-1564575/

also according to jenvey the 52mm should be pretty nice for up to 87hp per cylinder (348hp in total) nad given my overall measurements of throttleplate distance, trumpets, injector to plate ect, i should carry power well to 9800rpm
Throttle Body Selection with Jenvey Dynamics - Jenvey Dynamics


as of now my 52mm's are for sale and i am looking for 55mm or larger. but how big is too big?

jspinn13

the turbo build in my signature was 100% stock motor, stock intake, stock throttlebody, only e85 and a nice turbo setup.

GhostAccord

Yes, the bell mouth and air box design are key to top feed fuel injection.

OK so is this 13.5:1 as you mentioned in your original post or is it going to be an 18:1 build?

What fuel are you planning to run?
What is your target power band, RPM and red line?
What are the specs on the camshafts?

This information will change your CFM requirements and throttle sizing.

jspinn13

i will be using 13.5:1 pistons, but with h23 crank and longer h22 rods my compression will be bumped to roughly 17-18:1 depending on what thickness headgasket i use

i was going to use e85, but i am leaning more towards m5 at the moment

its going to be a track car, so top end is where it will be operated most of the time, cams and head will be able to carry power to around 9800+ but a dyno will tell where my power will end

the reaper cams that i mentioned are a 500+ lift camshaft, i will be clearancing my cam rails to make them fit

unusual71

yeah cam specs are on the DDTech site. i am curious how the "stage 3" compares to the reaper. only marginal differences in numbers but maybe the profile is different. I suspect you will need some really deep valve pockets in the piston if you are going to push this well beyond 9k rpm. by the time all is said and done im sure the compression will be coming down a bit. Based on the H-series chamber unless you have a REALLY tight fit between the piston dome and combustion chamber I suspect it is hard to achieve higher than 15:1 compression without welding the head and increasing the quench area. just my rookie observations/opinion though.

It is not exactly simple to run a huge cam in the H-series head. for examples, even with a skunk 2 pro2 (.490 ish lift I believe) on the intake side there is not clearance between the retainer and valve stem seal. First time I hit VTEC it choped up the seals and I had 8 intake valve stem seal halves in my oil pan (thankfully just the oil pan). I am not sure why more people dont mention this. I fully clayed the motor but turning the thing over by hand with VTEC locked was not enough to damage the seals. so despite all my best efforts there was still a MAJOR detail I over looked just because I assumed it would be posted all over the forums as every time someone asks what cam people usually suggest pro2s.

To really set the head up properly for a big cam the valve spring base, retainer, and how far the valve guide are pressed into the head (and even the valve seat for that matter) all come into play. I would personally run a stock length valve guide but sink it further into the head by about .080". slightly longer valves would also remedy the problem but I am not sure on the effect of changing rocker angles etc. and there is certainly not enough room for adjustment in the valve stem length alone. maybe if you started playing with base circle diameter but that's another topic..

Ghost covered it but yeah, the trade off between fuel mixing/atomization vs whatever flow is lost around the injector seems to always result in an overall gain when the injector is placed outside the runner. The first method is with a stand off mount like in Ghosts pictures. the "better" way is to have them mounted opposite the runner opening in the air box wall, with the air box wall contoured around each injector to smooth air flow. obviously this method requires more work and less packaging constraints. The ducati version is probably a result of packaging constraints but the overall difference is probably only like 1 or 2 hp anyways. The injector can't be mounted too far away though because the condition at the runner opening is actually quite turbulent and you start spraying fuel all over your air box pretty easy.

DDTECH

Different lobe profiles between the 3 and the reapers.

The 3s are very comparable, to the PRO3s, my camshafts in a few test have provided a little bit better midrange, while retaining the same top end as a pro3.

The Reaper camshafts are in a league of their own, period. No matter what anyone claims or says, they are the biggest for the B/H motor.
I original had them a 285 duration, and dropped it down to 280. The reason for this was because i was trying to give customers better v2v/p2v while staying over .50x lift, which in all honestly isn't really needed on a B/H head but some people wanted it so we designed what would work. Lift is effective duration, hindsight is 20/20 but there is a very big difference between our stage 3 and reaper.

The reapers aren't just sold to anyone. Special requirements are needed to be met before i sell this camshaft to people. They require notching of the cam rails at least thirty thousands.

TracerAcer2.2L

Thanks for the great "big cam" info unusual. Not sure I am envisioning your "better way" for fuel atomization as I don't know that I've seen that setup.

I'll need custom Reapers eventually, maybe by years end. Have some R&D on some other things to do first

DDTECH

Because simply put its nobody's responsibility except the installer/owner of the setup.

Installing a camshaft in the nature of a Pro2, 3, Reaper, etc.. require you to take extra steps. Measuring Rocker arm to Retainer clearance, Cam rail to cam lobe, and others. When you push the limits of things, you need to understand more goes into it.

The Average Joe may forget this and this is why there are true engine builders who do this for a living. When I put together motors these are things i regularly check and there are acceptable tolerances for each different setup. People do not quite understand that and first thing that goes wrong, they want to blame someone else, other then themselves.

unusual71

definitely. When you start getting into the really fine details you realize how many details there are and how many decisions to be made and it becomes clear why the people who do engines for a living charge what they do. there are lots of obscure "tips and tricks" or modifications when building engines that people have figured out over the years but there isn't a lot of information widely available about how to effectively apply all these things to different engines because that is the type of info that is harder or more costly to get.

you say over .500 lift has diminishing returns. is that because of the valve angle and the relatively tight valve to valve in these heads?

98vtec

Call Kinsler.