Twin turbo.....which ones???
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dirtytorque
Flusted
JNLRacing
mrbeige
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OddUnit :: The Workshop :: Engine
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Twin turbo.....which ones???
Would there be any benefit to running two turbos on a 16v motor? Looking at Rich's RX7 build just got me thinking. Could you run a small turbo then a big turbo (compound), or indeed one turbo per 2 cylinders?
so as not to confine this to 16vs, I've seen twin turbo setups on 24v VRs, so what would be the advantages/disadvantages on the 2.8/2.9 (12/24v) as well?
so as not to confine this to 16vs, I've seen twin turbo setups on 24v VRs, so what would be the advantages/disadvantages on the 2.8/2.9 (12/24v) as well?
Last edited by mrbeige on Fri May 29, 2009 7:27 am; edited 2 times in total
Re: Twin turbo.....which ones???
Somepicsof a twin turbo set up on an 8v crossflow longitudinally mounted in my RWD Mk1 that I may get to finish one day
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Long and short if you are going to run 2 turbo's you are best of running 1 per 2 cylinders of identical design and using the intercooler to mix the charge. This way you can get 2 small turbo's to produce 1 bar each giving a compound charge of 2 bar.
The benefits fatter torque curve with quicker spool up providing you get the maths right. Without a restriction of hp at the top end due to a small exhaust housing. Is it worth the hassle if you got the know how it can be fun.
Here's a 1.8t with 2 turbo's recently upgraded the engine and now making 635hp (first car on the page)
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Long and short if you are going to run 2 turbo's you are best of running 1 per 2 cylinders of identical design and using the intercooler to mix the charge. This way you can get 2 small turbo's to produce 1 bar each giving a compound charge of 2 bar.
The benefits fatter torque curve with quicker spool up providing you get the maths right. Without a restriction of hp at the top end due to a small exhaust housing. Is it worth the hassle if you got the know how it can be fun.
Here's a 1.8t with 2 turbo's recently upgraded the engine and now making 635hp (first car on the page)
[You must be registered and logged in to see this link.]
JNLRacing- .:Cammed:.
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Re: Twin turbo.....which ones???
Holy sh1t
Flusted- .:Cammed:.
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Age : 44
Location : Isle of Wight
Re: Twin turbo.....which ones???
I don't think we should have started this forum, I'm getting silly thoughts now...
I'm liking the quicker spool and fatter torque curve though. Do you think there would be enough room behind a 16v in a Corrado for two turbots? I guess you'd need to calculate the turbo spec based on a 1 litre engine then, given that it each turbo is only driven by 2 cylinders?
I'm liking the quicker spool and fatter torque curve though. Do you think there would be enough room behind a 16v in a Corrado for two turbots? I guess you'd need to calculate the turbo spec based on a 1 litre engine then, given that it each turbo is only driven by 2 cylinders?
Re: Twin turbo.....which ones???
^^^ lol have a look at the pics of the hulsen tuning setup be much the same so will give you a good idea of space
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As for working out the turbo size not as simple as that as you have to keep in account rpm and cylinder head flow not just cc. I opted for 2 x renault 5 T3's. I believe Carlo Hulsen went for a T2 equivalent of a saab originally
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As for working out the turbo size not as simple as that as you have to keep in account rpm and cylinder head flow not just cc. I opted for 2 x renault 5 T3's. I believe Carlo Hulsen went for a T2 equivalent of a saab originally
JNLRacing- .:Cammed:.
- Number of posts : 205
Re: Twin turbo.....which ones???
JNLRacing wrote:As for working out the turbo size not as simple as that as you have to keep in account rpm and cylinder head flow not just cc. I opted for 2 x renault 5 T3's. I believe Carlo Hulsen went for a T2 equivalent of a saab originally
What block are you using there then? looks like a 2ltr! And how come you went for 8v xflow? What CR?
ctwg60- .:Stroked:.
- Number of posts : 770
Re: Twin turbo.....which ones???
using a bubble block with 1.8KR crank in it. xflow for something different also the fact I could hang 2 turbo's of the side of it. CR is 8.5:1 the idea is to see what a highly tuned 8v was actually capable of reliably.
JNLRacing- .:Cammed:.
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Re: Twin turbo.....which ones???
Oh right sounds interesting have you used forged pistons? 2 bar sounds like a lot for cast but then you never know what they are capable of when mapped correctly. I'm using cast in my 2ltr 3A counterflow G60 engine and would be interested in your views on cast v forged.
ctwg60- .:Stroked:.
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Re: Twin turbo.....which ones???
I reckon you need to do a build threadJNLRacing wrote:using a bubble block with 1.8KR crank in it. xflow for something different also the fact I could hang 2 turbo's of the side of it. CR is 8.5:1 the idea is to see what a highly tuned 8v was actually capable of reliably.
Re: Twin turbo.....which ones???
\mrbeige wrote:I reckon you need to do a build threadJNLRacing wrote:using a bubble block with 1.8KR crank in it. xflow for something different also the fact I could hang 2 turbo's of the side of it. CR is 8.5:1 the idea is to see what a highly tuned 8v was actually capable of reliably.
I second that motion.
ctwg60- .:Stroked:.
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Re: Twin turbo.....which ones???
lol on the build thread it was one of the original build threads on E38 that kicked the trend of on there. The thread fizzled out as I stopped work on it 2 years ago. As business got too busy. It's currently being partially started again as i decided to make some chassis changes to it. It'll be one of those cars that will be done when it is and when it is people will wonder where it came from
However if you are interested I'll post a link in the build thread section to where the photographs of it are up until 2yrs ago.
However if you are interested I'll post a link in the build thread section to where the photographs of it are up until 2yrs ago.
JNLRacing- .:Cammed:.
- Number of posts : 205
Re: Twin turbo.....which ones???
As for forged vs cast
Rods are pauters and pistons are forged wiseco's. Personally wouldn't go much above 280hp/tq on cast although 325 has been seen reliably on old yank motors with an additional shot of 250hp of nitrous before the rings let go on one of the cylinders.
Rods are pauters and pistons are forged wiseco's. Personally wouldn't go much above 280hp/tq on cast although 325 has been seen reliably on old yank motors with an additional shot of 250hp of nitrous before the rings let go on one of the cylinders.
JNLRacing- .:Cammed:.
- Number of posts : 205
Re: Twin turbo.....which ones???
Link would be good. So why the kr crank in a 2ltr? I take it your using 83mm weisco G60 pistons and 136mm length rods?
ctwg60- .:Stroked:.
- Number of posts : 770
Re: Twin turbo.....which ones???
Rods are 144's with custom spec pistons but yes 83mm.
Originally I was going for 2 litres to get some extra torque but once I mathematically worked out the engine flow vs the head flow at different rpm levels I realised that the small capacity increase wasn't going to be worth it and I was better of going solid lifter with a high rpm high lift cam for max power.
As the block was already prept I just changed the crank and ordered the corresponding rods and pistons of my choice.
Originally I was going for 2 litres to get some extra torque but once I mathematically worked out the engine flow vs the head flow at different rpm levels I realised that the small capacity increase wasn't going to be worth it and I was better of going solid lifter with a high rpm high lift cam for max power.
As the block was already prept I just changed the crank and ordered the corresponding rods and pistons of my choice.
JNLRacing- .:Cammed:.
- Number of posts : 205
Re: Twin turbo.....which ones???
I see, I thought as much. If you go high rpm with 2 bar an extra 100cc is neither hear nor there at 7500rpm+. I understand.
How do you go about balancing the pressures between the turbos? Or is it just a case of joining the outputs and directing the flow to the intercooler?
How do you go about balancing the pressures between the turbos? Or is it just a case of joining the outputs and directing the flow to the intercooler?
ctwg60- .:Stroked:.
- Number of posts : 770
Re: Twin turbo.....which ones???
I'm a fan of twin turbo on flat and Vee 6s and 8s where you have 2 very defined and seperate turbo banks. Easier plumbing and more exhaust flow for better spool up. But on a 4 pot, I personally don't think the plumbing and other hassle is worth it for the gains, not when a single GT3071R could probably do the same job, if not better.
kevhaywire- .:Stroked:.
- Number of posts : 605
Re: Twin turbo.....which ones???
I'm just thinking of super quick spool, using two smaller turbos with small exhaust A/R maybe
Re: Twin turbo.....which ones???
JNLRacing wrote:Somepicsof a twin turbo set up on an 8v crossflow longitudinally mounted in my RWD Mk1 that I may get to finish one day
[You must be registered and logged in to see this image.]
Long and short if you are going to run 2 turbo's you are best of running 1 per 2 cylinders of identical design and using the intercooler to mix the charge. This way you can get 2 small turbo's to produce 1 bar each giving a compound charge of 2 bar.
The benefits fatter torque curve with quicker spool up providing you get the maths right. Without a restriction of hp at the top end due to a small exhaust housing. Is it worth the hassle if you got the know how it can be fun.
Here's a 1.8t with 2 turbo's recently upgraded the engine and now making 635hp (first car on the page)
[You must be registered and logged in to see this link.]
So a bit of an off topic thread resurrection but you obviously used a crossflow head to help with the engine bay configuration of twin turbos on a 4 pot but did you flow test the head before and after porting. Is it right that x-flow heads had bigger ports?
Last edited by ctwg60 on Tue Jan 20, 2009 5:59 am; edited 2 times in total
ctwg60- .:Stroked:.
- Number of posts : 770
Re: Twin turbo.....which ones???
Also how much does a x-flow head improve breathing other the standard counter flow arrangment in you experience?
cheers.
cheers.
dirtytorque- .:Charged:.
- Number of posts : 1101
Re: Twin turbo.....which ones???
xflow head flows pretty much the same as the rest of the 8v heads. It's just a lot easier when doing turbo, carbs or TB's as you don't get the heatsoak into the intake.
JNLRacing- .:Cammed:.
- Number of posts : 205
Re: Twin turbo.....which ones???
In which case, the X-flow head wont have any huge advantage over the counterflow when retaining the standard charger setup?
Re: Twin turbo.....which ones???
Right then! That was easy.
Why do you think vw did a cross flow 8v?
Why do you think vw did a cross flow 8v?
ctwg60- .:Stroked:.
- Number of posts : 770
Re: Twin turbo.....which ones???
Packaging I'd imagine, and also variations in performance/economy based on heatsoak. I would guess that all later 8v engines used cross flow.ctwg60 wrote:Right then! That was easy.
Why do you think vw did a cross flow 8v?
Re: Twin turbo.....which ones???
Yes I came to the same conclusion, it also allowed them to run plastic intakes! The 2.0 xflow engine also produced the same torque and power as the cflow but produced it 800rpm lower for torque and 200rpm lower for power but I think this can be contributed to other changes they made at the same time. So I think I'm not going to be the one to try to disprove anyone by doing a xflow 8v G60 engine.
Oh well my life just got a lot simpler!
Oh well my life just got a lot simpler!
ctwg60- .:Stroked:.
- Number of posts : 770
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