1145 replies to this topic

[siztenboots]

when with a turbo , you have a very small aperture for the turbine wheel

 

what you need to see on that graph is map and ignition

[Rosssco]

I wonder if this whole 2.5" manifold vs. 3" manifold carries any real weight - does it really make that much of a difference, I wonder.?

 

And is this based on actual science, or just the bigger is better philosophy..

[stu8v]

I wonder if this whole 2.5" manifold vs. 3" manifold carries any real weight - does it really make that much of a difference, I wonder.?

 

And is this based on actual science, or just the bigger is better philosophy..

 

On my impreza it was literally a night and day difference going from a 2.5" turbo down pipe to a 3".

 

Granted not scientific, but it felt better everywhere, smoother better response etc

[Rosssco]

 

I wonder if this whole 2.5" manifold vs. 3" manifold carries any real weight - does it really make that much of a difference, I wonder.?

 

And is this based on actual science, or just the bigger is better philosophy..

 

On my impreza it was literally a night and day difference going from a 2.5" turbo down pipe to a 3".

 

Granted not scientific, but it felt better everywhere, smoother better response etc

 

 

Yeah but that's a turbo (who's main enemy is back pressure), and a down pipe.

 

I'm not saying it doesn't help torque output, but I wonder if its possible to quantify the perceived issues are down to the difference in slightly different sized exhaust manifold primaries...

[Bargi]

Graeme, guessing this is the standalone not Dutch ECU? Can you go through and show other stats, eg: if it's wheelspin should see a matching difference in speed

[Graeme Lambert]

Graeme, guessing this is the standalone not Dutch ECU? Can you go through and show other stats, eg: if it's wheelspin should see a matching difference in speed

You're asking the wrong person Ray. It s standalone etc but I'm not with the car and haven't been present for mapping etc. Really need MBR or Sam from jamsport to comment on that to be honest

[Nev]

Any combustion engine is just an air pump. The primary mantra is that the more air you can shove though it with the least resistance, then the more power it will make. With a few specific exceptions, more or less any resistances will reduce this ability to make power. The secondary mantra is to try and promote torque at higher RPM, this is mainly achieved with cam profiles, turbo/SC selection and ignition tables.

Edited by Nev, 09 July 2015 - 03:17 PM.

[siztenboots]

true, and you need a pressure difference for flow to happen

[vocky]

the reason why the 3" exhaust was made for the SC was because the 2.5" was restricting power, simples 

[Nev]

true, and you need a pressure difference for flow to happen

That's the petrol's jobs, followed by the turbo or SC's job

[Nev]

Another thing that people often aren't particularly aware of is that the hot gas that comes out of the exhaust is many many times more voluminous than the gas that goes into the engine.

Lets take a typical example for a VX220.

Inlet volume of air = 1 unit
Inlet charge temps = 40 degrees
Exhaust gas temps = 850 degree

Based on the Charles Law, this means the exhaust gas is about 21 times the volume of the inlet charge. Just think about that for a moment and you realise that the exhaust pipe needs to be very much larger than the inlet pipes.

Edited by Nev, 09 July 2015 - 03:34 PM.

[Graeme Lambert]

the reason why the 3" exhaust was made for the SC was because the 2.5" was restricting power, simples 

So it sounds like we know what I need to do. I guess the best thing to do is send it for paint etc and fit a new 3 inch exhaust afterwards. What's people's thoughts on that? Sound sensible?

[Rosssco]

Why don't you drive it first and see how you feel about it currently, before fitting more parts?

 

It will still be rapid even being ~25bhp down on your initial expectations..

[ArticMonkey]

You've not even driven it yet Graeme. Just get it running on the road and worry about this blip in the map later. It you hadn't of posted the graph none of this would be concurning you right now so just take it all with a pinch of salt. Chris has said he can't feel the dip in his top end so I don't think you will either. If you do, then you can get the mani swooped out. Matt can do the adaptions on your downpipe like he did for Bill, and then go for another rr mapping session when the car has been run in alttle more.

Edited by ArticMonkey, 09 July 2015 - 03:46 PM.

[Graeme Lambert]

You've not even driven it yet Graeme. Just get it running on the road and worry about this blip in the map later. It you hadn't of posted the graph none of this would be concurning you right now so just take it all with a pinch of salt. Chris has said he can't feel the dip in his top end so I don't think you will either. If you do, then you can get the mani swooped out. Matt can do the adaptions on your downpipe like he did for Bill, and then go for another rr mapping session when the car has been run in alttle more.

Not far off a good point there stu I won't be driving it until next spring now anyway as it needs to have bodywork etc sorted before that can happen anyway. Plus the wedding isn't far off so that'll soon be taking up a chunk of my time. I can't help but feel I should bite the bullet and optimise it now rather than wait til spring then find I'm disappointed. I won't lie, I wasn't blown away by the power figures even before I saw the graph, and having spent all the money on the harrop etc I'd rather get what I can from it. Otherwise for around 25bhp less I could've just used the m62 and a lot less cash...

[Graeme Lambert]

You've not even driven it yet Graeme. Just get it running on the road and worry about this blip in the map later. It you hadn't of posted the graph none of this would be concurning you right now so just take it all with a pinch of salt. Chris has said he can't feel the dip in his top end so I don't think you will either. If you do, then you can get the mani swooped out. Matt can do the adaptions on your downpipe like he did for Bill, and then go for another rr mapping session when the car has been run in alttle more.

How long until you're running anyway? Will be an interesting comparison.

[fezzasus]

Another thing that people often aren't particularly aware of is that the hot gas that comes out of the exhaust is many many times more voluminous than the gas that goes into the engine.

Lets take a typical example for a VX220.

Inlet volume of air = 1 unit
Inlet charge temps = 40 degrees
Exhaust gas temps = 850 degree

Based on the Charles Law, this means the exhaust gas is about 21 times the volume of the inlet charge. Just think about that for a moment and you realise that the exhaust pipe needs to be very much larger than the inlet pipes.

 

not entirely correct. You want to maintain high exhaust speeds to enable scavenging of air from the cylinder. This is why exhaust valves are typically smaller than inlet valves. We are not dealing with static volume here, it's all about flow rates.

[ArticMonkey]

You've not even driven it yet Graeme. Just get it running on the road and worry about this blip in the map later. It you hadn't of posted the graph none of this would be concurning you right now so just take it all with a pinch of salt. Chris has said he can't feel the dip in his top end so I don't think you will either. If you do, then you can get the mani swooped out. Matt can do the adaptions on your downpipe like he did for Bill, and then go for another rr mapping session when the car has been run in alttle more.

How long until you're running anyway? Will be an interesting comparison.

I guess if you're waiting that long for the car then using the down time makes sense. The making of the mani and downpipe adaption won't effect things apart from your bank balance at the end if the day. I and many others have got lost in mayhem of your build, and what your end goal turned into. You've pretty much got an exact like for like engine apart from you have forged pistons for added saftey. I don't know if that's effected your compression ratio or if Matt just retained the Saab head gasket? Only other thing is the double valve springs, which again are more a saftey net for higher rpm (7600+). Your build should safely see 350 with a 2.8 pulley and then we can find out if your extra cooling mods help sustain that power. If not then it'll be a meth kit or knock the power down with a bigger pulley. The differences are your custom harrop and plate, plus the intercooler. This might be the trigger for your loss or might be nothing at all. However you have a more controllable ECU and there for should have a better map. I fitted my new exhaust earlier today and my pump is in the post from spitfire engineering. So fingers crossed I'll be turning the car over this weekend. Touch wood I've resolved all my electrical gremlins so I can go for a drive. Providing all is fixed, I could possibly do a power run for people to fight over .

Edited by ArticMonkey, 09 July 2015 - 04:25 PM.

[Graeme Lambert]

 

 

You've not even driven it yet Graeme. Just get it running on the road and worry about this blip in the map later. It you hadn't of posted the graph none of this would be concurning you right now so just take it all with a pinch of salt. Chris has said he can't feel the dip in his top end so I don't think you will either. If you do, then you can get the mani swooped out. Matt can do the adaptions on your downpipe like he did for Bill, and then go for another rr mapping session when the car has been run in alttle more.

How long until you're running anyway? Will be an interesting comparison.

I guess if you're waiting that long for the car then using the down time makes sense. The making of the mani and downpipe adaption won't effect things apart from your bank balance at the end if the day. I and many others have got lost in mayhem of your build, and what your end goal turned into. You've pretty much got an exact like for like engine apart from you have forged pistons for added saftey. I don't know if that's effected your compression ratio or if Matt just retained the Saab head gasket? Only other thing is the double valve springs, which again are more a saftey net for higher rpm (7600+). Your build should safely see 350 with a 2.8 pulley and then we can find out if your extra cooling mods help sustain that power. If not then it'll be a meth kit or knock the power down with a bigger pulley. The differences are your custom harrop and plate, plus the intercooler. This might be the trigger for your loss or might be nothing at all. However you have a more controllable ECU and there for should have a better map. I fitted my new exhaust earlier today and my pump is in the post from spitfire engineering. So fingers crossed I'll be turning the car over this weekend. Touch wood I've resolved all my electrical gremlins so I can go for a drive. Providing all is fixed, I could possibly do a power run for people to fight over .

 

 

Well paint realistically in my head is going to take 2 months and I'm allowing 1 month for finishing the interior work, depending on all lead times etc. I've missed my bodyshop slot so many times now, I can't expect them to take it straight away. Add on another month for some final fettling of some other bits and we're already looking at mid November. I get married end of October...

 

No point in putting it back on the road for Nov onwards since the roads are likely to be their least suitable for a car like this at that time of year. Plus my insurance deal means that while I'm paying F/all for it currently based on a laid-up policy, as soon as its put back on the road the remainder of the year's balance will need paid, which would amount to around £500 for a few months. All from the original plan of having it on the road by now... That insurance is up for renewal in January I think so would time perfectly for finally getting it on the road next spring.

 

Agreed there are a few other elements that could be causing it. I expect the in-line cooler in the intake isn't one though, simply as Lee had his on when mapped also and didn't notice any adverse effects. And yes, I was certainly sold the benefits of the EMU ecu as being more controllable allowing a better fine-tune that should have found any extra numbers that may be beyond the realms of the safetynet (understandably) installed on the Dutch software.

 

There is a slim chance we can grab a full 3-inch system and bolt it to my car temporarily and do another power fun, though that won't happen instantly, and my gut feeling is that this is a sensible move. It might prove an easy fix, or alert us to the fact there may be something else causing the strange figures/graph. 

 

Re the engine and goals, I've not been made aware of the compression ratio or how it was achieved. I know the pistons were machined to custom sizes after calculations by Matt and his dad, but that's all i know. And yes, supertech valve springs should allow safe high rpm running, which is kind of why I wanted to stick with the 2-litre (since that should promote such behaviour).

 

Anyway, a quick and rough recap for everyone off the top of my head before I head home from work...

 

Saab B207 retaining 2-litre capacity with custom machined forged pistons but stock rods

Stage 2 ZZP cams

Supertech valve springs

Harrop Supercharger from ExigeV6/Evora with 2.95 pulley

Pro Alloy sandwich cooler in custom casing to fit lotus-fit charger

Standalone EMU ECU

Siemens 630cc injectors

Standard in-tank fuel pump as lifter, 044 as main pump feeding a swirl pot, using braided fuel lines

Phenolic spacer (ZZP)

ITG air filter (ala JG spec)

2.5-inch tullet manifold with 3-inch MBR twin silencer exhaust system

 

In my head I was hoping for slightly over 300 at the wheels (so thinking around 340-360bhp at the crank) but maybe I was just being unrealistic. Whatever the final peak power I was looking for, I was looking for a more progressive delivery of the numbers. Otherwise I should have done what George said and just gone standalone on my mint Turbo 

 

And yes, definitely looking forward to hearing the results of yours once you've done a power run mate. 

 

 

 

 

 

Edited by Graeme Lambert, 09 July 2015 - 05:02 PM.

[fezzasus]

Full 3 inch system you say...