Compressor Surge - Grand National

[xBaDaMaN]

sounds broken



[DaPepsinator]

so good

[SuperRODAR]

k onda con eso

[Exticy08]

change to a higher psi BOV spring or rase the psi rate if you have an ajustible BOV

[JLDG4]

@Exticy08 Or just give the engine better supporting mods for the turbo, So it can move more air...

[boost4fun]

@EviL80iE

No, it was too much turbo at part throttle. It was fine at WOT. A Godzilla BOV fixed it.

[EviL80iE]

@boost4fun hey thanks for ur reply, so its fair to say a faulty boost controller and or BOV can cause ur car to vent boost wile the throttle is open?

[boost4fun]

@EviL80iE

I accidentally deleted your original comment - sorry. An improperly sized turbo coupled with a lack of a BOV was what was causing the problem. The turbo was very efficient and was making a lot more boost than the engine could ingest at lower RPMs. The pressurized air backs up in the intake tract and causes the surge. A BOV fixes it by venting boost when there is a big enough difference in the boost between the intake tract and beyond the throttle body.

[copleygsxr]

What is your egt

[boost4fun]

It's a turbonetics T-70 ball bearing turbo. The EGT will creep into the 1700s on a 1/4-mile run, but are typically much lower than that.

[copleygsxr]

Is it a stock turbo

[racisrain]

diz vid really made me understand

[Mikecom32]

Great example of true surge! Thanks for the video!

Grand National love man, those things are sick.

[boost4fun]

Thanks! Surge is very misunderstood. Rather than get a smaller turbo, I tweaked the engine to move more air (heads, intake and cam). All better.

[WhatAFluke]

hey man just curious as to where u got ur gauges and gauge pod?

[frankvtec88]

good call, good compensate buddy. Good on you for taking the difficult but better route! Any vids of it after your mods? I'll just cruise through your vids. Grand Nationals are one of my fav. cars!

[crazy8sx08]

@boost4fun did u keep the car an auto or swap in a 5 speed?

[boost4fun]

@crazy8sx08 It's the stock 200-R4 auto. 

[metalseanhead]

You guys are idiots, surge sounds cool but it can actually kill your turbo.

IF you don't sort it out though it will split your compressor wheel nut off, which destroys the thrust bearings and bends the compressor blades backwards.

SO you guys are dicks for not sorting out compressor surge when it occurs. you don't deserve a car if you want to destroy it cause it sounds cool to do so.

[Tieuw]

but what if you place the throttle plate before the compressor?

[boost4fun]

Then there would be no way to regulate the boost - you'd get full boost all the time.

[454sskilla]

wat exactly is compressor surge someone please tell me

[RalfMilo]

when you let off the accelerator the throttle plate closes and the incoming air from the turbo has no where to go so it tries to escape the same way it came in through the compressor.

[gameratwork]

This kind of compressor surge is the bad kind that can wreck your engine. Its basically where your turbo is trying to compress more air into your engine than the engine can physically swallow, so it causes the turbine to accellerate.

[gameratwork]

Its nothing to do with your map or anything, your turbo simply is to big. Your Compressor wheel is obviously to large for the size of the engine and so at half throttle the turbo is compressing to much air for the engines cylinders capcity resulting in the superflous air being compressed along with the intake air to cause faster rotation of the turbo. 2 fixes mate, stroke your enging but do not touch the turbo or reduce your compressor wheel size and housing size.

[ilovefastcarslots]

wow i would be scared for my motor.

who chose the turbo? it sounds to me like the map is wrong for your engine since it was surging at full boost.

thats the bad kind of compressor surge here

[boost4fun]

I chose the turbo. It doesn't surge at full boost, only at part throttle. At WOT and 25-30 PSI it was fine. I've since put better heads and a much bigger cam in the car., so it's no longer an issue.

[ilovefastcarslots]

oh okay that makes sense glad to see it fixed.

those are nice cars i wish i had one

[QuantumTechMan3000]

that surge is surely not good for anything....especially ur engine im guessing u have a blowoff valve with a rubber diaphram from the sound of the surge....

[boost4fun]

In that video I had no BOV at all. That's the sound of the compressor surge through the 4" intake pipes. As I mentioned earlier, I think I need a better form of boost control. With the new heads, I now have boost creep as well.

[bpunlife]

now that is def compressor surge half the videos on here are fluttering wastegates.

[IamMonsterMan]

Is this in CT?

[boost4fun]

It's in NJ.

[nitrousboy0311]

OMFG IS THAT BOOST SURGE I HEAR? dude plz stop that kills the enigine and turbo you are overspoolin the turbo get a bigger turbo

[boost4fun]

It doesn't hurt the engine. It can damage the turbo, which is why I was trying to get rid of it. The problem is that the efficiency range of the turbo wasn't matched to the engine. In a sense, it was too big, not too small. The surge is from the turbo moving too much air for the engine to ingest. I recently put better heads with bigger valves and a bigger cam in the car. Since the engine can move a lot more air I don't have any more surge with the same turbo.

[APontiacof455cubes]

but it seems like it could work the other way too. If the turbs are too small, then all the exhaust on the other side would be backed up because of the increase in power from the intake flow, with new heads.

[flatthump]

WHat are you using for boost control? The throttle plate position has a lot to do with it.

If you aren't already using an EBC, you might try it.

[boost4fun]

I'm just using a brass bleeder valve. I think an EBC would fix it, but the BOV is working for now. It bleeds boost away at part throttle and closes at WOT.

[sullengirl99]

you would be better off getting a external waste gate that would bleed the pressure alot better than the blow off valve. then atleast getting a manual boost controler. i really think that is your main concern since you cant let the excess boost out and over boosting causing your fuel cut

[boost4fun]

I don't have a fuel cut - I can make boost until the heads pop off :-). But you're right, I would've been better off with a more sophisticated means of boost control rather than the BOV. The BOV is still useful, but not for part throttle surge. I think an external gate is my next move.

[sullengirl99]

im pretty sure a t70 is a big enough turbo.

[tradesmansassistant]

:)

nice sound

[Thetornprince06]

what kind of cam do you have. ive been looking to get a bigger turbo.

[boost4fun]

In that video I had a 206/206 flat tappet cam. With that cam and a 61mm turbo the car ran a best of 11.3. The engine came apart this past March and I just fired it back up over the weekend. This time I have a 218/212 roller cam which seems to be better matched to my converter and the T70 turbo that you hear in the vid.

[Duvorack]

What size turbo? What size engine?

[boost4fun]

It's a Turbonetics T70-BB turbo bolted to a 3.8L V6. The ball bearing turbo spools too quickly. I just rebuilt the engine and had a substantial amount of head work done. It is capable of moving much more air now so hopefully the surge is either gone or moved to a better place in the RPM curve. I'll know in a few days when I fire it up for the first time.

[chancekirksey281]

This company called DCR does anti-surge work to turbos all day. There good at there work

[Syclone0044]

This is a very good video of compressor surge!! Thanks for creating this! My Syclone did the same thing with a stock motor and PT51 turbo, but I never captured it on tape like this..

[boost4fun]

Thanks. What most people don't realize when they watch it is that the surge is happening at part throttle. It's not jug when I let off the gas (which is where a BOV/BPV helps). I haven't been able to cure it yet. Clearly the turbo is too big for the engine at part throttle but it works great at WOT.

[synaptic1]

You need a Synchronic BOV

[boost4fun]

How is it different/better than the Turbonetics Godzilla valve I have now? Will the Synchronic BOV cure the part-throttle surge you see in the vid?

[synaptic1]

I just read your reply above. You should google the phenomenon called "DV Flutter." The Synchronic will not cure it, but it should open and close if there is a pressure differential between pre and post throttle pressures at part throttle. I think that the problem with the Godzilla is that it isn't sensitive enough to oscillate the BOV at part throttle so that, at least, the turbo isn't getting the brunt of the pressure rise due to the surge.

[synaptic1]

Where do you live? You should try to find a shop that is doing our try-before-you-buy program so that you can test drive the product to see if it can do anything for you.

[boost4fun]

It's bad, sort of. It's making more boost than the engine can use at part-throttle and starts that 'chugging' sound. If you could see the boost gauge you can see it jumping around. Theoretically this is bad for the bearings on the turbo. I've tried a couple of things to get rid of it but haven't been successful yet.

[cheng001]

is that good or bad? I have a GN too, and this never happen to my car before? What's going on there?