Inlet and exhaust upgrades???

[Guest]

ORIGINAL: 944Turbo

ORIGINAL: porschphile
Sorry guys, I can't ever seem to keep my posts short and condensed. I'd highly recommend picking up a good thermodynamics book and start reading! Much of it is really common sense and understanding thermodynamics can really help you further understand forced induction.

Impressive first 5 posts [] forgot to say welcome to the forum!
Tony

Thanks! Sorry they are so long! [] I've been in the 944 community for a few years and am by no means all that experienced. Porsche's are first and foremost my absolute favorite cars since I was about 4 or 5yrs old and got a model 930 for a birthday present. Though, I started off in the import world and with all of the technology that is so widely available for those cars it's really opened my eyes to the possibilities still awaiting us 944 owners to unlock even more power and further optimize our cars.

 

[333pg333]

Yes P-file is a guy whose words I respect from R-list and I thought he would have some good and interesting points to be made here so I'm very glad he took up my offer to contribute to this site to add to the already valuble posters that exist here. I've also asked another guy who is an engineer that does excellent headwork and related modifications to join in. The more qualified and experienced people to partake on this site can only add to it's existing reputation.

 

[evil 944t]

P-file is correct. In many ways.. where do I start..

I bench tested an extrude honed intake (just to clean the cast imperfections) and found that the 1 and 3 cylinders are getting less air than 2,4.

Do you want free HP?? I do. This is what I did. I use a flow bench to do this. This is not "guess" work!! real testing.

I took the stock intake and cut slots in it and inserted deflectors in it. I re directed the air so all the runners get the same flow. It works through a very large cfm range. I doesn't restrict any of the runners, it just evens them out.

Now that you have the same air flow in each cylinder, you no longer have a "rich" situation in 1 and 3. You now have the proper a/f's in each cylinder, freeing up HP!! Thats free HP people!

On to P-files 2nd correct statement. Yes the throttle body is to small. I tested a bunch of sizes until I maxed out the intake and found no more gains. NEWS FLASH!! The stock intake cam move a ton of air, if you free up the plenum and T-body.

It can surpass many vendors "ported" heads. The MAJOR problem then becomes the IC. Its the next major bottleneck.

The bottom line is. Everything works well in stock form. Thats what it was designed for. When you increase CFM by 10% or more over stock, its out of design.

The key is to design it to work together, just like Porsche did. There is no way in the world to build one part and have it be the end all to your problems. You have to first flow the head(your most limited factor) to achieve you HP goals and then design everthing else to support it.

I have flowed many vendors heads for people and found many were 10-20 cfm over stock. Thats very dissapointing. they claimed cfm numbers are mind blowing to me. They claim more or equal cfm than I can make and I oversize valves ports etc..

I changed both intake and exhaust valves to large valves. Then I spend 10-20 hours going between the flowbench and the grinding bench to get the gains I get. I have also gone past the point and ruined a couple heads to find that you can install valves that are too big and that you can oversize the ports too much.

You can do alot with the turbo heads exhaust side without touching the ceramic port but you are limited. Believe it or not, you can get it to out flow the intake side by 30cfm!

The last thing to address is the cams. If you have a modded car, throw the stck cam in the garbage ASAP!!! Its killing your top end. Even if you go for the mildest aftermarket cam, it will better than what you have.

I have found there are few cams that are perfect for the one motor that has different mods done to it than the next. It doesn't work that way. Its possible to grind a cam that helps you retain midrange torque and give you a stronger top end. Also, its very possible to put an adjustable cam gear on to help dial in a huge radical cam with out killing your low speed torque.

I hope you enjoy my finding as I look foward to see what others are doing. There is lots of HP to be made from these engines!

 

[333pg333]

Thanks Evil for comming aboard on this one. I hope that it continues to delve into the subject. Fen, Rick, Jon, Scott, Tony amongst others are all guys on this site that have done plenty of work to 944's and I'm sure can add to this post along with you and P-file.
Keep it coming guys. This can only be good.

 

[eastendr]

Nice to see some Rennlisters over here.

Welcome guys! [] []

I'm looking forward to posting some new real-world data next year when I get back to work on WUF. There's a few things in the pipeline there.

Also on my 944S (baby WUF) as well - mainly head and port work along with ignition and mapping tweeks.

This is potentially one of the best threads for a long time - real innovation and not sales blurb.

Keep it rolling!

 

[944Turbo]

And a welcome to evil too !
Tony

(UK952 on rennlist)

 

[Indi9xx]

Indeed an interesting thread!

I wish I could say more about one or two items I have in the pipeline relative to this thread... But all will become clear sometime next year. Although I am more than happy to continue discussion that will not give too much away.

Its also nice not to feel quite so alone in the quest for real power, furthering the 944 turbo and discussing development, rather discussing whats currently available which has often been developed to make meaningless big numbers or sales bumf.

On the exhaust side of things its amazing just how much detail you can go into on each and every part of the system.. Having spent a lot of money and time this year working on wastegate entry/exit pipes with Tial wastegates for the 944 turbo (with help from some of the worlds top performance design engineers) you would not believe just how far this tiny part of the 944 turbo exhaust can be improved apon to make a package which not only works, but due to detailed analysis and trial is an elegant solution with benefits beyond the obvious.

The rest of the exhaust, comprises of many parts, each of which with their own chalenges, losses and improvements to be found.

"Thermodynamics" is a phase that I am also very happy to see being used.. especially in the turbo application. Far too many people missunderstand the turbocharger and think of it as just a exhaust driven windmil, rather than its true method of operation which draws only a small amount of its energy from any windmill effect, but from the thermodynamics of how gasses react to tempreture and pressure differentials... Sometimes I even wonder how many of the turbo manufactueres in the 944 scene understand this! Let along the designers of some of the current 944 turbo exhaust system, which seem to completely miss the point and potential improvements which can be made for very little production cost to exploit the thermodynamics at play within the system and their effects on the turbo.

Intakes and exhausts can be very much overlooked. Its the fine details which often reward those who are prepared to put in the effort required.

 

[Hilux]

I would have thought that the inlet would have to be carefully designed with varying `constrictions` or `tapers` as required so as to maintain volume whilst equalising pressures in each cylinder due to the unequal length of each intake. Longer will need to be tapered to maintain the same pressure? Exhausts are another black science but it is clear that equal length and diameter exhaust headers are vastly more efficient in removing/pulsing exhaust gasses.

I would also have thought that the introduction of individual throttle bodies would mean v v accuarate fuel metering and distribution to each cylinder. When I was in the kit car (Westfield) arena there were many cars experimenting with bike bobble throtties. Some of those bike throbble botties have enormous choke dia and potential for huge fuel supply/power

Regardless, personally I have always gone for a tried and tested overall package of parts that complemented each other rather than a gradual bolt on single part upgrade

 

[Guest]

Thanks Evil 944t! It's nice to hear that some of my suspicions weren't too far fetched. If you don't mind, I'd be curious to know your opinion of some things as you seem to be a very knowledgeable guy. In stock form, or say up a little higher around the 300-350whp level, what do you feel would be a more optimal throttlebody size? Judging by what I've seen from Nissan 200sx's, 240sx's (the stateside 2.4l version of the 200sx), and various other 2.0-2.5l i4's it seems like a 60-65mm TB would provide a nice increase in throttle response and would free up intake flow a decent amount. Unfortunately the IC pipes would still be a restriction though.

I'm building my 944t and shooting for the 600rwhp range. In the near future I'm going with a Darton MID sleeved 2.5l block and ultimately converting to a 944 S or S2 16v head. There are of course a ton of other modifications that I want to do to handle this power level, though it's probably too long to list here at the moment. I'm going to be using a fairly large Garrett Gt35r setup to acheive this power level. I actually should be receiving the turbo setup, from a company here in the US, this coming week. Right now, it's going on my relatively stock motor while I build another one on the side. I'm limiting my stock motor to moderate boost/hp levels as it will be awhile before I can finish a built motor. Anyways, I just figured some of you might be interested to hear it. If anyone's interested, I can post more about it once I receive the parts and get everything going soon. There are some of us out there that still want to push the limits! []

I've been thinking about using a 70mm throttle body for around the 600hp level, as it would be a huge improvement over stock with such a high amount of airflow. I would preferrably like to maintain a throttle response that isn't overly sensitive, as too big of a throttle body can cause. However, judging by some of the non-944 4cyl cars that I've seen pushing around these power levels, it sounds like I might even want to go a little bit larger like a 80-90mm TB. I'm thinking a 90mm might be a little too sensitive, though I'm wondering if the reduced airflow restriction might be worth getting used to an overly sensitive throttle? At the point that I reach those airflow levels, if there is another 20hp to be had , a decent decrease in intake air temperature, and/or slightly less boost required to acheive the same power level then I feel it would be worthwhile to me even with the loss of some precision in the throttle. Evil 944t, any thoughts on sizing for my specific application?

Also, I had one other question Evil 944t. Do you happen to remember the length of the intake/exhaust ports on the stock 8v heads? I know they are relatively short compared to most modern DOHC i4's, though I can't remember exactly how short and I don't have my 944 head here at the moment. I'm toying with the idea of just doing some simple/inexpensive mods and a custom cam on the 8v head and using that for awhile with the built bottom end I'll be doing. I'm not too fond on the idea of spending too much money on the 8v head, as it just seems like too much of a restriction compared to the 16v heads considering the power levels I'm looking for. Ultimately, the 16v heads might provide slightly less peak torque, though generally when properly modified the 16v units should maintain tq/hp much higher and flatter in the rpm over a modded 8v. That's not to say the 8v couldn't support the airflow, but I think by that point it could be more of a compromise than the conversion to a 16v. Ah, there is just too many things to think about! []

 

[333pg333]

Travis, Evil is actually stateside as well as you. I think Jon sounds like he might be doing something with the intake as well. I can't wait for someone to start posting results too. I'm sure Rick will be along soon as he is doing similar things to his 'WUF'. Petnames are big in England by the way. I've named my car NINA partly as it's close to 9 which is the prime Porsche number and also as she reminds me of the German punk singer of the '80's. Proud and defiant! Showing my age here.[8D]

 

[evil 944t]

Travis,

I don't recall the length of the runners off the top of my head. I would have to measure them. The intake and exhaust ports on the head are something like 110.40cc and 99cc.

Now, I would like to add, All the work I have done is to max out the performance of the stock intake. That being said, it still doesn't mean thats your best way to go.

You really need to design an intake that suits your engines output. The only reason why I went through all that trouble was that I was hoping it would keep me from building one from scratch.

The stock intake I modded, works great. It flows plenty. I believe it to be better than any aftermarket attempt. Because it wasn't a theory. The stock manifold was meant for that stock application and now, its still mated up to the same parts but, its just moving more air.

If your interested in the throttle body and intake info, please pm me. I would rather not make that public knowledge becauses I have a lot invested in it and I have people that compete with it. I would rather them keep their/my edge,

I can tell you that, if you go too large, you will out flow the intake. Keep in mind, as soon as you increase the t-body and intake to match the head, you bottleneck at the IC. If you change the IC, then get working on the exhaust system.

I run a cup car 4" system but it will be changed to almost a straight dump tube. This is a track only car. It will run the least restrictive muffler I can get away with to keep db's down at the track.

In my opinion, This is all great but it shifts the WHOLE powerband to the right. You can move it around with the proper cam but not much.

A "Honda type VTEC" system would be the best. On our 16v motor we fooled around with the vario cam and it does work on the turbo car. Don't get excited though. It does not give you V8 torque and F1 revs. It just smoothes everything out. You can't really have your cake and eat it too, lol..

You need to address this as a complete system and have realistic goals. Then through proper design, parts selection (including turbo), planning and tuning. You can achieve some pretty good, usable HP/torque. BUT!! this does not come cheap. You can spend 2-3 times what the cars worth so be realistic. A track car that you'll always keep, to me, the sky is the limit. I love my car and will keep it until I believe the motor can no longer be improved. Then I'll move on tho the next motor.

 

[Guest]

Evil 944t, thanks for the info on the head!

I completely understand about the intake. I fully realize that I will need a much larger plenum, TB, different diameter/length runners, etc to support the much larger volume of airflow I am shooting for. I also completely understand the basics on designing some of these things, such as tapering the runners, introducing a slight angle forward to rearward taper to the plenum, etc to still maintain decent airflow velocity with these larger components. I was asking about the stock intake purely for educational purposes, and considering a much lower power goal in mind (definitely not for my purposes). It's nice to hear that even the stock intake has a little room for improvement for some slightly higher power levels, and that was the main thing I was wondering about. Modifying the stock intake would save everyone quite a bit of money if they were only going for a more moderate 250-350rwhp

 

[333pg333]

So if you're not going for the whole top end focus but more mid-range then it must be possible to tailor a system that both improves over stock but keeps some of the good torque. Especially out of an engine with increased capacity.

 

[evil 944t]

Yes sir, you are correct. You can make everything breathe and use a smaller turbo so it spools up faster too. It depends on how much top your looking for. There are a number of ways to skin this cat.

 

[333pg333]

Ok lets assume that you've purchased all the goodies that make up this engine what do we use to control it? Should we go for standalone or do we get someone we trust to write some chips and piggyback/massage the signal? What's the general concensus here?

 

[Fen]

I'm sure it's not the general consensus, but I think standalone. It is not a surprise to Paul that I think his engine is lovely but hobbled by the EMS.

I think using the Motronic is fine up to a "bolt-on" level, but when you get to the point of needing to run big injectors (and I don't mean 55# ones) you start to see a failing of the Motronic in terms of the choice that work with it and also the ability to drive big injectors at small openings for good low speed manners. Also you have few options for ignition control compared with standalone, all the solutions for replacing the AFM (and you are going to do that, right?), even those very few that work well, are a cludge as they have to fool the DME into thinking it has an AFM at some level. Also the Motronic implementation in the Turbo has seriously limited (to put it mildly) temperature compensation as Rick has pointed out before.

With a good standalone you get free choice of injectors, ability to drive large injectors at low volumes with accuracy, sequential injection, sequential ignition, integrated boost control, knock contol, MAP, much better engine modelling software (or at least many more set points on the fuel, ignition and boost maps). In addition you can have stuff like WOT upshifting, variable boost per gear, traction and/or launch control, VVT / water spray / nitrous activation. Lastly you have the ability to easily switch between maps and to relatively quickly remap to accommodate future changes to the engine.

 

[eastendr]

Standalone. 110%.

Far too many limitations with the DME and KLR.

Standalone takes you to another level of capability and really start working in sympathy with 'proper' engineering modification as we are discussing here.

 

[Indi9xx]

Motronic is amazingly flexible with all things considered, its agreed that beyond a certain point your fighting a loosing battle.

We are working on MOTEC at the moment and the possibility of for plug and plug use including synch trigger for sequential use, along with off the peg maps for many configurations (2.5, 2.8, 3.0, 3.2 and various turbo's), so at least people can get their car running "well enough" without experience of motec (of course dyno tuning would get the best out of it)... More on this once there is concrete news.

I think both the current 3.2 customers are planning on going Motec or aftermarket EMS once their wallets have recovered. But its amazing how well we have managed to get the 3.2 running on the standard KLR and DME with C-H chips, B I G injectors, no ISV and B I G turbo. BUT.. the thing that will hold back the 3.2's is the intake, exhaust and to an extent the EMS... But replacements for all these 3 parts will be available next year.

 

[eastendr]

Yes, but this has all been available for some time. (excepting that it is NOT plug and play if you have to start implementing separate phase trigger sensors for sequential injection and ignition, separate PROPER charge air temp sensor etc). Why no ISV ?

Bob at Random EMS has been able to supply this for some months based on the extensive base mapping on WUF and his own cars including GT spec racers and large capacity configurations. This is already proven reliable and thoroughly tested in both road and race conditions.

There are a number of 944's that I know of in the UK that have been running standalone for some time (with widely varying results).

Ultimately, the more tuners implementing standalone for the 944, the broader the spectrum for owners will be. As usual, all that glitters is not gold and a considerable amount of time is needed to iron out the installation with good base mapping and things like cold start, sensor calibrations etc.

All of this takes a long tome to get right, before moving on to full mapping whch MUST be done or there is no point going to standalone. The costs of this are seriously high to do properly for each individual vehicle to make the whole thing worthwhile.

As always, the market for this will be extremely small with a very limited number of owners willing to spend such a large amount of money on a 944 for what is a later stage of upgrade compared with the initial cheaper chip / turbo / exhaust type mods.

 

[evil 944t]

Rick,

I agree. Standalones are not new. I have had a motec m48 on my 3.2ltr for a year. Autronics and Motec are nice. There are a couple more but I personally have no experience with them.

Jon,

None of this can really be plug and play. There are way to many factors. You can build and sell custom harnesses, thats the easy part. A start up file is also easy but, I would not let anyone try to tune if they have know idea how to.

I have about 8 hrs on a ENGINE dyno. That got me pretty much right where I wanted to be. Its a little harder to do on the chassis dyno. I will be adding a new intake, turbo and header so guess what, back to the dyno.

This adds up to huge $$ that most people can't justify.

On anouther note, there are some US tuners that broke the motronic code and they run 72lb injectors no problem and are making 600rwhp with a modded factory DME, wasted spark etc..

Anythings possible, It just costs money.