Exhaust Back Pressure And Boost + 13b RX7 Drive By Wire | Today At HPA 212 [UPDATE]

[@hpa101]

Want to watch the members-only webinar on Supercharger Selection along with over 200 other lessons on engine building, tuning, and wiring topics? Sign up here for only $19 USD a month, start and stop at any time (unlike your gym membership!). Gold Membership subscription: www.hpacademy.com/register - Taz 👨🏻

[@giftidnz0]

I've used the BMW M3 throttle actuator to drive a set of Toyota 4age quad throttle on my Mazda BP engine, controlled by a Haltech Elite 1500, works very well!

[@timobrien6916]

I absolutely love the way Andre talks. So wise and articulate!

[@Cliff_Anderson]

Great explanation...especially as it relates to overlap and cam selection. You mentioned this in passing but I think it's important to reinforce that the energy in the exhaust is helping spin the turbo, and this energy is in the form of heat, not just pressure. So it is entirely possible (and desirable as you stated) to have a greater pressure in the intake then in the exhaust. It seems at first glance to be a "something for nothing" situation when you just examine pressure alone, but the heat energy is the contributor that makes it work.

[@JD-oh1kb]

Right before you released this episode I was scouring youtube for info on running an LS throttle body on a modified 13b manifold 🤙🏻

[@Popes_Projects]

Jameson Dahn Full Function Engineering makes an adapter for this. I’m using on mine, I also opened up the 3 holes and it’s now one big triangle. Using a Subaru pedal and AEM infinity.

[@JD-oh1kb]

Thanks for the info Pope! 🤙🏻

[@dcptiv]

2005 honda accord drive by wire system can be used as a great conversion. Uses cable from pedal into a box that transfers physical input to digital for the DBW throttle body. No need to change the std pedal at all.

[@minilogoguy18]

Could always use the old 03-07 USDM Honda Accord V6 APP sensor since it's remotely mounted. You can keep the original pedal and just run the old throttle cable to it to get your pedal position.

[@fnky143]

Bless the NZ closed captions of "MESDA" instead of "MAZDA" 🤣

[@hpa101]

Isn't that how you spell it?

[@jacquesgold]

Similar to the "Wise-co" pistons....🤣 I shouldn't say too much, they drilled us in the "creckit"........😁

[@SachAlvarez]

the massive problem I see with your remote egp setup is that, by reducing the temperature, the pressure will change (PV=nRT). you should do the math in order to implement some sort of ecu compensation so that you get the correct reading.

[@zacharymorris9917]

Excellent point, but you're comment would be correct when applied to a static system; NOT this application. In a continuous supply system, like this, the pressure will not change with temperature so long as there is no major restriction between supply source and pressure transducer.

[@ChutneyInc.]

I fooled myself. Please give us 7s more more info. about your fd's backpressure since it doesn't have a valvetrain? So maybe info on the size turbine wheel and exhaust housing size? A bunch of us could really benefit. I love how educational you all are. Thanks a much!

[@dj4monie]

Rob Dahm did some testing of different housings on his 3 rotor, he still had some back pressure issues at high rpm. Installing a pressure sensor will take a ton of guesswork out of selecting the proper turbocharger.

[@ChutneyInc.]

@@dj4monie thanks. I done more research on the matter. I still want to know what A/R they will be using on there turbo. I know other rotary guys are interested as well

[@jasondayberry5942]

Secondary plates are for cold starts. they are just as restrictive as the primary plates after warming up.Why remove them ?

[@run_stop_restore]

Are you going to use the Throttle Bypass Valve on the 13b or do you plan to control Idle Speed only via the DBW System? I'm building basically the exact same Setup right now (DBW'd 13b, EFR8374, Street Port, etc) but i'm still undecided on the DBW Setup. My initial Plan was to use some sort of Bosch Motorsport TB on an adaptor like the FFE one but you have a good point with the Double Throttle and Airflow Separation between the UIM runners. The idea behind going DBW though, was to get rid of all the additional Stuff on the Intake System (AWS, ISC, etc ) and i'm a little worried that the remote mounted DBW system is not capable of running precise idle control without a Bypass Valve. I think the E46 also runs a bypass in stock form.

[@hpa101]

In most instances with a DBW throttle I use the throttle body for idle control and it works exceptionally well. It can get a little tricky to gain really accurate control though if you're using a really large TB as even a tiny change in blade angle makes a big difference to the airflow. DBW and ISC were incorporated together when DBW was relatively new but you won't find ISC necessary with modern DBW TBs and modern control strategies.

[@run_stop_restore]

@@hpa101 Thanks for the reply. "Modern" DBW systems are not remote controlled with an external actuator though. Anyway, let us know if it worked out on the FD, i'll copy it then :) .

[@GroovesAndLands]

Where is the link for the wiseco giveaway?

[@hpa101]

I knew I forgot to put something in the description sorry. That one has finished just recently, however, here is the next one: gleam.io/fb/Yk0ZG Best of luck! - Taz.

[@mikka1986]

About the exhaust back pressure graph, it looks kind of weird how is it possible the turbo manifold pressure stay atmospheric after full throttle applied and boost start to build? I'm using a "budget back pressure gauge" setup which tapped from manifold to an analog boost gauge, I always see back pressure start to rise before boost pressure, almost 2:1 at certain engine speed, it's a catless full exhaust system. A friend of mine with direct pipe setup told me he never see below 1:1 too. Is this the magic of high tech turbo?

[@hpa101]

It's not magic, but rather just to do with turbo sizing. Modern turbo technology has allowed us to get better response without needing to strangle the turbo and cause high back pressure. Everything is a balance though and for a given turbo, less back pressure will result in more power at high rpm but less response. It's quite common for factory turbos to produce a pressure ratio of 2:1 as the manufacturers are focussing more on response than outright power.

[@zacharymorris9917]

Modern VGT turbos on compression ignition engines can easily achieve 0.5:1 on a OEM turbo.

[@gregpieris4478]

Quite pleased with myself that you picked up on my comments on remote DBW actuators in this latest vid! (Do I win a prize? 😁)

[@ATLRIOT]

I’ve seen people drill out the 3 butterfly valves and put on large one instead. Then replace the cable with a RX8 drive by wire. Wouldn’t that be easier and cheaper?

[@gregpieris4478]

Yes you can do that but then you lose the staging of the primary vs secondary port induction. Having primaries only increases response and torque at lower rpm, throttle angle and off boost

[@IHadToMakeThisAccount]

what or why do you guys say exhaust pressue it really lazy? doesnt it just seek the easiest path out? Wouldnt it just go to the shortest nearest exit vs all the way out the tail pipe?

[@danielbrealey2924]

That wastegate position still isn't great. It looks like it's fitted at a 90 degree angle, so the exhaust gas IS having to make a sharp bend to exit out the gate. Most quality manifolds that have been well thought through will have the gate positioned in a manner where it runs at way less than a 90 deg angle to stop boost spiking. The closer the gate flow is to the direction of flow through the manifold the better it works... Bloody Kiwi's... Maybe give Kyle @6Boost a call and see what a good Aussie manifold looks like... 😜

[@hpa101]

Yea I pretty much covered everything you just mentioned in the video. As I mentioned, in this particular instance given it's an engine swap there's very little space and hence the options are limited. This is a base manifold designed for an S-chassis and there's more room for the wastegate integration. In our case Sinco have done the best job possible given the packaging constraints. There's the ideal world and then there's reality. While we aim to get as close to ideal as possible, we still live in the real world and sometimes compromise is necessary. What i can guarantee is this integration is going to work a LOT better than the original mockup which had the wastegate solely coming off a single runner.

[@danielbrealey2924]

@@hpa101 I agree it will work better than taking it from one individual primary runner (which of coarse is never going to work) but having a 90 deg bend is so far from ideal that I think it still may give issues with boost control if you end up chasing some proper power. If it's only going to push low numbers on low boost an oversized gate for the application will hopefully keep the boost under control- but I wouldm't be surprised if it's an area you'll end up having to do a little more development on and try and change the angle of the gate to flow at least a little closer to the direction of flow of the exhaust gasses. I don't want to come across as you're average know it all keyboard warrior, I actually have 19 years experience as a qualifed mechanic in Australia and do a lot of this kind of work for customers, friends and of coarse myself. Being someone in the trade, I like the channel. A lot of it is aimed at your average enthusiast- but some of the tech and stuff is still good to see. One of these days I'll cough up some cash and have a look at your tuning coarse, as it's one area my knowledge set could be better. Cheers

[@danielbrealey2924]

@@hpa101 I know this is stating the obvious, and in some ways can be argued that this option is not ideal either- but the gate itself doesn't have to be mounted right on the manifold. In the same way you have to have less than ideal bends in manifolds themselves and snake primaries through where you can, you can run an extension pipe to the gate and mount it in a semi- remote fashion and therefore leave yourselves room to have a more favorable flow in terms of direction from the collector. It would require fab work to be done while the engine is already in to package it all properly, but it would work a lot better than a 'gate mounted at a 90 deg angle. I think this might be the best they can do without building a set up in the car and being restricted by using this off the shelf manifold (the position and length of the collector is limiting 'gate position- if the manifold looped down a little lower in the bay it would allow for a slightly longer collector and to run a pipe off the collector to the remote mounted 'gate), but most decent fabricators could do a pretty good job of this if given the car with the engine already fitted. Just a thought. Will be interesting to see how this all plays out...

[@mr.valentino2824]

Hey guys, A little off topic. I have a 2013 BMW X5 xdrive50i. I want to modify or even better, Delete the air mass sensors. How can I or what is available to do this without going standalone?

[@Kj16V]

"Weebinars" 😆 Seriously tho, I do love these Weebinars 😃

[@kaioser]

back pressure should be illegal

[@jahir1204]

Zack is gone?!

[@hpa101]

Yes, we miss him =( Zac lived about 6 hours away so was just here for 4 days a week but with a young family it was a bit too much time away from home so he's ended up taking a role that was offered to him at a University close to home. Feel free to peer pressure him to return though, I do it all the time myself haha - Taz.

[@curvs4me]

Tanx André, we've got forum master techs claiming that anything less than 3:1 exhaust/boost pressure is fine. Really anything more than 1.8:1 and you will make more power supercharging.