Boost increase
Submitted: Tuesday, Oct 21, 2008 at 18:42
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Mudripper
Hi all. Hope I don't get under your skin with all these recent turbo questions, but I did a little experiment with my exhaust system. I disconnected the exhaust from the back of the turbo and went for a drive (I got fumigated a bit in the process.) I noticed an increased boost of around 10-15 kPa. Is it normal to have such an increase without the exhaust connected? The pleasure of hearing the turbo whistling much louder was indescribable! But I wouldn't have it like this permanently of-course.
Any thoughts?
Cheers.
Reply By: Member - Tony B (QLD) - Tuesday, Oct 21, 2008 at 19:57
Tuesday, Oct 21, 2008 at 19:57
Any thoughts? MMM. I do not think many would disconnect their exhaust and try this, so sorry can not help. But what are you trying to achieve? Cheers Tony
AnswerID:
331093
Follow Up By: Mudripper - Tuesday, Oct 21, 2008 at 20:04
Tuesday, Oct 21, 2008 at 20:04
I'm not really trying to achieve anything apart from finding out if having such a difference in boost pressure with the exhaust on and then taken off is normal, that's all. I'm just hoping that the exhaust is not causing some kind of restrictions due to soot build up, etc.
Cheers.
FollowupID:
598860
Follow Up By: Member - Tony B (QLD) - Tuesday, Oct 21, 2008 at 20:15
Tuesday, Oct 21, 2008 at 20:15
Mudripper. Fair enough. Will see if someone knows. Im an old petrol head so can not answer that question, though as an ex hoon, I can agree the sound of a motor under power can be music to some ears. My old HoldenV8 through sidepipes gave such a sound. These days I still like the power but quite is the best. Regards Tony.
FollowupID:
598862
Reply By: Member - Mick O (VIC) - Tuesday, Oct 21, 2008 at 20:20
Tuesday, Oct 21, 2008 at 20:20
Mudripper,
Sorry if I've missed your previous posts. What are you driving? Have you gone to the many 'vehicle specific' sites to seek feedback? May be an option that'll get you more feedback.
Cheers
Mick
(3L TD Patrol "Grenade" driver who has replaced everything!)
AnswerID:
331097
Follow Up By: Mudripper - Tuesday, Oct 21, 2008 at 21:32
Tuesday, Oct 21, 2008 at 21:32
G'day Mick,
I'm driving a Toyota Landcruiser 1976 HJ45 3.6Lt diesel with an aftermarket turbo (RotoMaster, size AR60.) I'll go to the
places that you have suggested and might even go to the Landcruiser site.
Cheers.
FollowupID:
598873
Follow Up By: traveller2 - Wednesday, Oct 22, 2008 at 08:44
Wednesday, Oct 22, 2008 at 08:44
Be very careful, some of the early kits for the H motor used the exhaust back pressure to limit boost. That motor wasn't particularly strong and you may cause damage if boost is too high.
Does it have a wastegate?
FollowupID:
598920
Follow Up By: Mudripper - Wednesday, Oct 22, 2008 at 09:43
Wednesday, Oct 22, 2008 at 09:43
Traveller2,
Yes, I'm aware of the H engines having some weaknesses and I did think about the back pressure having some effect on the turbo. Apparently the H engines have a habit of cracking heads?
It doesn't have a waste
gate. The maximum pressure the I'm getting is around 25-30 kPa if I really give it to her up a
hill (with the exhaust on). So it's not a great deal of pressure compared to what other people have in different vehicles. But I am usually light on the throttle anyway.
Cheers.
FollowupID:
598932
Reply By: Member - Oldplodder (QLD) - Wednesday, Oct 22, 2008 at 09:35
Wednesday, Oct 22, 2008 at 09:35
Noticed the same thing on my Pajero when I recently replaced the 2.125" stock exhaust with a 2.75" exhaust, new (bigger) dump pipe at the rear of the turbo, and free flow muffler.
Less back pressure, so the turbo spins up sooner at lower revs, and at the same throttle at lower revs, puts out more boost.
Less turbo lag.
The waste
gate still controls the maximum boost though at higher revs.
And the turbo whistle is louder.
Now if you want some fun, and be a kid again, check you have a blow off valve on the manifold and turn the waste
gate up high or disconnect it.
Then you get a good big whoosh as maximum boost is hit, even louder than the ricers. Get's the
young blokes thinking, and laughing at the old fart in the 4wd.
The wife reckons I am regressing, I warn her that the day I stop being a boy, she will miss it.
AnswerID:
331178
Follow Up By: Mudripper - Wednesday, Oct 22, 2008 at 09:54
Wednesday, Oct 22, 2008 at 09:54
Yeah, I was thinking of buying a BOV and even replacing the muffler with a resonator. I took (by stating the things that I'm doing, it looks like I have a lot of time!) the muffler off and went for a drive and it wasn't much louder. Since the 2.5" exhaust stops just behind the cabin, I might get it extended to the back of the vehicle and not bother about a muffler.
Cheers.
FollowupID:
598940
Follow Up By: Member - Oldplodder (QLD) - Wednesday, Oct 22, 2008 at 12:57
Wednesday, Oct 22, 2008 at 12:57
Did something like that to my standard system.
Very basic low resistance muffler at the rear, and took out the resonator under the drivers
seat.
Got a bit of a droan up though sitting at a 100, specially at the back
seat.
New system with a matched muffler gives more power and is quieter.
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598969