Possible answer to the old debate? IC VS CC

[JJ]

Mike Jonno Neil Johnson !

[Mikejc]

Oops I did'nt spot that last few posts. Sorry Neil and thanks JJ lol

Mikejc

[Mikejc]

Obviously it would seem that Pace has got it a little wrong regarding their C/C only being able to flow 1.0bar. Their are more than a few of us now pushing more than this through it with no sign of restriction

Mikejc

[campbellju]

P.S. Lotus Esprit turbo - chargecooler

P.P.S Porsche 911 turbo (1993) - Charge cooler

On the ST205, Toyota chnaged from an intercooler to a charge cooler to stop heat soak from the engine. This is also a problem on other mid and rear mounted engines.

Why do people keep talking about boost and intercoolers??? Assuming you've not got a cheap one made of fudge then you should easily get 2 bar without bursting it.

Horsepower and charge temperature are related Boost pressure and charge temperature are related, cooling efficiency and intercooler/charge cooler size are related, pressure drop across the IC/CC and its size are also related. some posts seem to be mixing things altogether and coming up with rubbish.

An IC and a CC is very car and application dependant.
Stuck in traffic all the time, CC
Constantly above 60mph, IC

I've just fallen into my own trap of sweeping generalisations but people should stop comparing apples with bananas

IMHO, a CC is more appropriate for a road going '2. If you're building a drag car, why not stick the IC above the engine bay in the direct air flow rather than messing around with funneling it through to the boot. Anyone seen the RS200 pikes peak car in EVO recently that did exactly this

[nutter]

arrrrghhh!

I need answers! I've just sold my greddy I/c cos i thought the pace option would be better suited to my needs. I think i will need to run more than 1.2 bar on my turbo (td06) to get it into it's efficency range. I just wish someone would come up with a definitve answer! anyone who said saving up for parts is the hard part is wrong! It's choosing the parts when you have the money!

For christmas can i have a book that tells me exactly what i need to fit to my 2 to make it work properly. Thanks santa

[JJ]

The only thing I've bought wrong is this ruddy MR2 turbo !

I look at things on an industrial level ( not always good ).. but working on petrochem sites, the better cooling medium for any device on site has to be with the use of coolant / water around a liquid or gas that requires heat to be pulled from it - unless its electrical... then the option is only using air.

It should be always common sense to realise if the engines in the back, then the CC is obviously the way forward .. had the engine been on the front, I'd have a great big ruddy front mount that would replace the bumper !

Ideal world would be to have pipes trapsing to the front end of our cars, but compressing that volume of air would cause ever so many problems on the turbocharging / responce side of things.

[raptor95GTS]

er depends on where you measure this 1.2 bar in the manifold is gonna be 1.2 bar no matter what turbo is boosting ergo the same amount of airflow.

Took a while for me to be lead to that conclusion but when you think about it, its right. Yes a bigger turbo will provide cooler air so there will be a difference in the amount of air but that's purely down to the temperature difference.

A "bigger" compressor WILL give more mass flow rate at the same boost, which is what you're interested in. I say "bigger", but what is factually correct is "more efficient". It's the compressor's efficiency for a given boost pressure/flow rate that affects how much the air is heated up by. That's why a good IC upgrade can yield better results than a turbo upgrade because you can make a bigger improvement to intercooler efficiency.

Having said that, some recent turbos have very efficient compressors, although it's difficult to tell compared to stock because I've never seen a flow map for a stock CT26 or "CT20b".

agreed yes a bigger compressor will give more airflow at the same boost. However 1.2 bar boost in the manifold is going to contain the same volume of air independant of the actual turbo used to generate it.

as you say with a bigger compressor the air temp will be lower for a given pressure thus increasing the air mass ergo giving more air to play with but I haven't sat down to work out the differences.

However a bigger compressor will be able to supply said 1.2 bar boost all the way to the redline whereas the std units will tail off as they run out of puff. That's the most noticable benefit of bigger turbos

[jonno]

Found a little more out today. It turns out that Neil Johnsons car recieved the prototype Pace C/C. This i'm told had a different core from the one's sold now! So it may be the case that the one's now availible will not suffer as Neils did. Something I hope to prove in time...

I also learned some more regarding Neils visit to Thor to have his car tuned. It turns out that on his first run he was indeed able to flow more than 1.2bar (1.7bar I believe), but from there things went wrong for some unknown reason as yet. But in short. After that first good run his car would make no more power with any more boost than it could at 1.2bar. Something not right there I think?

For more tech info regading the above please contact Patrick at Rogue Systems

Mikejc

Hmm, I beg to differ

We actually ran 1.9 bar of boost through the original CC core, however we only got about 20 bhp more than when we ran it at 1.2 bar. I am not saying that when you go over 1 bar the universe ends - I am saying that the turbo duty cycle has to be increased more than you would expect. This means that the exhaust is having to drive the turbo harder and you loose power. Essentially I have proven the Pace core upto 1.9 bar, I have also proven that over 1.2 bar you dont get the returns you really should. Pete from Thor spotted that once the car was warm we were able to get one really good run at say 1.7 bar but then the power dropped off due to det, for each run afterwards - this turned out to be from cylinder temperatures getting too high - the turbo was having to work so hard to squeeze the air through the CC core that exhaust gas was building up inside the cylinder.

Physically the core is quite small, much smaller than the Spearco IC and Greddy IC for example. I calculated a surface area of 145cm2, compared with the ST205 of ~240cm2? Obviously size isnt everything but its a good pointer.

I have just driven the car back home with the "new" core, didnt seem a huge amount different to be honest but it was wet and I was having difficulty stopping the rear wheels spinning. I will test again once the roads are dry.

Mike : Just relax, the Pace CC is a fantastic device - I am just pushing it slightly harder than they intended, that doesent mean its rubbish ok?

Be happy

[Mikejc]

Hi Neil.

I am very happy with it to be honest mate I'm just annoyed at those who rubbish the Pace C/C just because they have read or heard from someone elso that it is no good. I have been trying to do my home work/research by calling Pace direct but it would seem that the guy that originally worked on the first C/C has since left! It's good now that you have come forward and helped paint a clearer picture though buddy. At the end of the day i'm simply trying to optain the facts surronding the Pace C/C so that I inturn can learn yet more about tuning and also pass that knowledge onto others

So far i've only been able to peice together small parts of the story from verious different sources. But I must state once again that I am nothing but satisfied by the results the C/C have left me with.

So in short, where do you think the limits of the C/C sit. Boost wise, power wise (at the hub's please) ???

Very keen to know how you get on with the new core also mate?

Mikejc

[MR2Mania]

agreed yes a bigger compressor will give more airflow at the same boost. However 1.2 bar boost in the manifold is going to contain the same volume of air independant of the actual turbo used to generate it.

as you say with a bigger compressor the air temp will be lower for a given pressure thus increasing the air mass ergo giving more air to play with but I haven't sat down to work out the differences.

I'll help you out...

Volume flow rate has the units of:
metre (cubed, to give volume)
seconds (time)

Mass flow rate has the units of:
kg (mass)
seconds (time)

Note, to get from one to the other, the difference is DENSITY.

Units for density are: kg/m^3. Hence you can see that if you knew the density of the air, you could work out the mass flow rate from the volume flow rate.

Density of air is reliant on the TEMPERATURE of the air, so if the compressor is more efficient (ie adds less heat to the charge) then the air temp will be lower. Since the volume and boost are the constants, the diffference is the density. You get a more dense charge if the air is colder (hence more mass of air, hence more power).

HTH.

[jonno]

So in short, where do you think the limits of the C/C sit. Boost wise, power wise (at the hub's please) ???

I suspect that the limit is somewhere about 330bhp at the hubs. Upto that point you dont notice any ill effects at all, once you go further you can run more boost but you just dont get a great deal more power. As for a boost limit it depends on your turbo, currently my GT28 produces that power at 1.2 bar and no matter how much boost we drive through it we dont get much more power and start to run into det after a few runs. We didnt too much analysis with my old CT26 since we didnt realise it was a problem

[raptor95GTS]

agreed yes a bigger compressor will give more airflow at the same boost. However 1.2 bar boost in the manifold is going to contain the same volume of air independant of the actual turbo used to generate it.

as you say with a bigger compressor the air temp will be lower for a given pressure thus increasing the air mass ergo giving more air to play with but I haven't sat down to work out the differences.

I'll help you out...

Volume flow rate has the units of:
metre (cubed, to give volume)
seconds (time)

Mass flow rate has the units of:
kg (mass)
seconds (time)

Note, to get from one to the other, the difference is DENSITY.

Units for density are: kg/m^3. Hence you can see that if you knew the density of the air, you could work out the mass flow rate from the volume flow rate.

Density of air is reliant on the TEMPERATURE of the air, so if the compressor is more efficient (ie adds less heat to the charge) then the air temp will be lower. Since the volume and boost are the constants, the diffference is the density. You get a more dense charge if the air is colder (hence more mass of air, hence more power).

HTH.

I'll help you out! cheeky git I am actually aware of the physics behind it thank you, a degree in engineering does come in useful sometimes especially the flow analysis The bit I negleted to think about previous was where the boost was being measured.

If the boost is being measured from the outlet of the turbo then the bigger the outlet the more air flow for any given pressure. Since we are measuring within an enclosed space that hasn't altered volume then 1.2 bar is 1.2 bar and the only thing as you say that alters is the temp of the air hence the density and thus air mass thus the amount of air available to burn with fuel.

However the difference in power is reckoned to be about 4bhp for every 10degC

The big plus for a bigger turbo is its ability to supply a constant 1.2 bar or whatever boost right up to the engines redline thus giving you more power at the top end

< if I have missed anything its because I'm still drunk from last nights works xmas night out >

[MR2Mania]

I'll help you out! cheeky git I am actually aware of the physics behind it thank you, a degree in engineering does come in useful sometimes especially the flow analysis

Sorry mate, wasn't meant to be condescending - was just trying to help out. I too am an engineer, and have been doing these calcs, day in day out, for the last couple of years, so was just trying to offer from info from my experiences.

However the difference in power is reckoned to be about 4bhp for every 10degC

The big plus for a bigger turbo is its ability to supply a constant 1.2 bar or whatever boost right up to the engines redline thus giving you more power at the top end

The one thing to remember is that without the compressor map for the stock turbos, you can't honestly say how much more efficient another turbo is. I used to run 18-19psi (midrange only!) on my Rev1, but I'm pretty sure that the temps were through the roof. So, the CT26 could create the boost but was more akin to a hairdryer in terms of efficiency. And as you say, it couldn't hold boost at high revs, but then again it's a puny compressor wheel.

There's a lot of info on a compressor map to tell you how it'll perform. For example, many people even neglect the "turbine speed" lines, which essentially tells you how fast you must spin the compressor to get the air flow and boost that you want. An example would be the Greddy TD06. It's got a nice efficient compressor and gives good power for moderate boost. It's helped along by a turbine side that keeps it spinning at the right speeds so that it stays within its efficiency ranges, but its downside is that the turbine side will become restrictive at a certain point (basically, the complete turbo has been specced to make the most of the compressor, and therefore doesn't like to run too high a boost, unlike the Garrett GT turbos).

[raptor95GTS]

I'll help you out! cheeky git I am actually aware of the physics behind it thank you, a degree in engineering does come in useful sometimes especially the flow analysis

Sorry mate, wasn't meant to be condescending - was just trying to help out. I too am an engineer, and have been doing these calcs, day in day out, for the last couple of years, so was just trying to offer from info from my experiences.

yeah I know you didn't mean anything by it, absolutely no offense taken by me It was the first thing I read this morning and it did make me smile. Its been over 10 years since I did that stuff so I'm well rusty in that area anyway. It's great when people explain things out as its nice to understand WHY something does what it does rather than accept it does, please don't change your style of replies. If people are going to get offended everytime something is pointed out to them, they should stay away from forums

Turbo charging / supercharging is a science but as you have pointed out it totally depends on what your needs are. If you want a screaming top end then bigger the better for the turbo size but if you want drivability then you do need to understand the physics behind it and to be honest I don't understand enough about that side of it.

Since i have no intention of changing the turbo anyway its something I don't need to know but hey it might come in useful in the future as things do eventually wear out / break

[Mikejc]

Seeing as though you two seem to know so much about turbo's etc. You can help my decide which new one I should be picking for my own car...please

I'm looking for something more efficient most of all, that will not leave me with the dreaded lag. Driveability is key here!

Currently the car is pushing 293bhp @ the hubs which I must say is nearly enough for my liking, but some more power would'nt be a bad thing, just not at the cost of loads of lag.

In short I don't want to over kill for my needs here, if that makes sense?

I've been looking at the Power Enterprise PE1919T. It would seem that this turbo offered all and more as to what i'm after but some more opinions would be great Heres some info for you to look at... http://www.madpsi.net/MR2PEKit.htm You can also find some more info on their own website too a believe.

If you look at the power graphs you will see that full boost does come in a little late but then the fact that the car being used is totally standed might have something to do with it. ie standede exhaust and cat etc!

Thanks for any help guys

Mikejc

[raptor95GTS]

hi mike, sorry but I get my head round how these things work and I know the CT20b on the rev3+ is bigger than the CT26 on the rev1/2 but really I have absolutely no idea on what turbo you could never mind should buy . I'll look at the website but really I can't say which turbo is best / better worse.

Obviously you use the car on the road so you'll want something to pull from near enough where it does the now, but that's my knowledge all used up.

Currently the car is pushing 293bhp @ the hubs which I must say is nearly enough for my liking, but some more power would'nt be a bad thing, just not at the cost of loads of lag.

I seem to remember you saying that about the 240 odd you had some 6 months ago. Heh heh, this time next year you'll be on the 400BHP scent. Go for it

edit - JJ, steve C etc would be better bets on this. Maybe start a new post solely for turbo choices? get it noticed more

[MR2Mania]

Seeing as though you two seem to know so much about turbo's etc. You can help my decide which new one I should be picking for my own car...please

Sure mate, no worries!

I've read that page, and I knew basic details of the turbo before, but whether it's the right choice depends what you're after. I'll come to that in a bit.

The above article is factually incorrect in a few areas (eg comparing dynapack to dynojets - dynojets can't vary the load, because they're an inertia dyno, whereas the dynapack is a proper load cell, just that it measures at the hubs instead), so for me, it sounds like sales talk straight away. It doesn't show compressor maps or anything, just says "supports 400bhp at the turbine". So do a lot of things, but they won't make 400bhp with *any* old compressor. It compares itself to the GT25, but for me the GT25 is one of the least best GT series turbos to start with.

I reckon you can find another Garrett GT that would work out cheaper, or the same, but would produce better results. If you want great spool up, but no more than 360fwhp, then go for the GT28RS (also called the disco potato), but if you want to go for more power, then the Garrett equivalent of the HKS GT2835S is the one to go for.

Note though that the Garrett GT series turbos tend to need a fair bit of boost to get good results. Obviously, you won't get the best out of these turbos if you're on the stock bottom end. IMHO, I think the limit of the stock pistons is about 1.5 bar - above that, and the ringlands crack. The safest level to run on a regular basis is 1.3bar.

So, if you're trying to get the most out of a stock motor, you need to choose a turbo that flows well but at low boost levels. For example, a TD06 is near it's limit above 20psi, so with a stock bottom end you're likely to get the best out of it, if nothing else breaks! :S

Incidentally, I'd guestimate that your 293ATH is about 313-318bhp at the fly. I've seen a LOT of MR2s on dynos, and have come to see what kinda losses you get.

[Mikejc]

I'm planning on running no more than 1.2bar whilst i'm still useing the standed internals. Like already mentioned i'm near happy with the current power but i'm un-happy with the fact that my CT20b might well give up on me and leave me with a costly engine build. So something more reliable/efficient is what's needed, and some extra grunt won't be a bad thing so long as it's not at the cost of loads of lag!

I'll see if I can find out a little more about the PE1919T. I must admit that I like the fact that it's a direct replacement, not to mention how cheap I can get it also!

That aside, you think the GT28 is worth looking into? Given that I only plan on running 1/2bar.

Mikejc

[Rogue]

Anyway, what does Patrick @ Rogue say? After all, he's selling these kits?

As a rule, I try not to comment on threads specifically about our products. I think people tend to trust the opinions of customers with experience of the product more than someone with a financial interest in them.

When we initially decided to make a chargecooler kit for the MR2 with Pace Products, we purchased a stock revision 2 MR2 turbo specifically for their use as a test bed. That way there would be no constraints over development time.

As it happened, TOTB3 was just around the corner and Neil Johnson (Jonno) was desperate to resolve his cooling issues before the event, so we agreed to use his car for prototyping. Once this was complete, Pace then turned their attention to the revision 2 turbo we had supplied them with, and installed a chargecooler kit built from the jig designed on Neil's car.

It is possible (and we believe likely) that the prototype core supplied for Neil's car is different to those used in the production kit. Mid-way through the project, the person at Pace responsible for the MR2 chargecooler project left the company, so even Pace are a little unsure about that first kit. It may be that due to time constraints an off-the-shelf design was used, rather than one that fulfilled our brief of "1.5bar all day along and as much as 2.0bar on special occasions"! This is by no means certain though, so Pace have sent Neil a replacement core which they believe will meet his flow needs, and will examine his old core in the new year.

As a side note, I would add that the belief that Neil's chargecooler is proving to be a restriction is as yet unproven in anything other than theory. No-one has yet physically measured the pressure drop across the core.

Some of you may also remember that Mike JC had some issues fitting his chargecooler kit, and there was some concern over which revisions of MR2 it would fit and whether it would work with transplanted engines etc. We have since been able to check over Mike's car and discovered that the rubber isolators designed to minimise pump vibration against the chassis had been installed on the chargecooler core by mistake, causing the rest of the pipework to align incorrectly. We'll ensure that this is highlighted in the instructions in future.

No-one has pushed the chargecooler kit anywhere near as hard as Neil has yet, although we have had one car (with a production spec kit) that ran for a while at 1.3 bar on a hybrid CT26. Boost pressure has since been reduced as it ran the engine close to the edge of it's fuelling capability and also because it scared it's owner!

If anyone's got any specific questions about the kit, then please contact me directly.

Best regards,

Patrick Mortell,
Rogue Systems Limited
02476 226677

[nutter]

well there you go then All we need now is for Mike to push the boost up to 1.5 bar then we will have proof that the current pace CC is not a restriction. SO come on Mike do it for the imoc community. I know you'll probably blow everything up but hey .. it's for the good of all mr2 owners