VTT Double Barrel Review.

[martymil]

Its much cheaper than getting the single and upgrading to double later.

As I was running e85 at the time the single just fell flat on its face after 5000rpm and needed the second pump.

Maybe its just my pump, not all are the same but e85 has some major demands on the fuel system.

With the double barrel I was able to get it running perfect and making loads more power everywhere on e85 but that came at a cost and I was forced to rebuild the engine with full forged internals.

Today I scaled back my power needs, even just on 93 its a real handful to drive on the best of sports tyres without going to a semi slick, breaks traction in third between 3 to 4000rpm and that's not running full boost but slowly ramped.

I'm upgrading my turbos because I was given the opportunity and will be doing a flex fuel setup for track days but for street
93 is more than ample.

To the point of the story, no matter what tune I load up and what power level I'm seeking the double barrel accommodates all my demands when set up correctly with the appropriate tune and supporting mods to the point where the car cant be driven because it wants to kill you at every turn. LOL

Its been running flawlessly for over a year now with absolutely no issues or at least not related to the pump.

There is only one issue I have, the car keeps wanting to rip the diff out of the cradle when ever I drive the car hard and I even replaced the factory 10.8 diff bolts with much stronger 12.9 and it still wants to shear them off.

 

[dyezak]

Its much cheaper than getting the single and upgrading to double later.

As I was running e85 at the time the single just fell flat on its face after 5000rpm and needed the second pump.

Maybe its just my pump, not all are the same but e85 has some major demands on the fuel system.

With the double barrel I was able to get it running perfect and making loads more power everywhere on e85 but that came at a cost and I was forced to rebuild the engine with full forged internals.

Today I scaled back my power needs, even just on 93 its a real handful to drive on the best of sports tyres without going to a semi slick, breaks traction in third between 3 to 4000rpm and that's not running full boost but slowly ramped.

I'm upgrading my turbos because I was given the opportunity and will be doing a flex fuel setup for track days but for street
93 is more than ample.

To the point of the story, no matter what tune I load up and what power level I'm seeking the double barrel accommodates all my demands when set up correctly with the appropriate tune and supporting mods to the point where the car cant be driven because it wants to kill you at every turn. LOL

Its been running flawlessly for over a year now with absolutely no issues or at least not related to the pump.

There is only one issue I have, the car keeps wanting to rip the diff out of the cradle when ever I drive the car hard and I even replaced the factory 10.8 diff bolts with much stronger 12.9 and it still wants to shear them off.

View attachment 13597

You need solid dif mounts. The flex of the bushings twists the bolts. And might as well go to an M3 diff while you do that.

On a side note has anyone noticed any vibration with the Shotgun? I have a slight vibration with mine. Between 2500-3500rpm it feels like an electric toothbrush or electric razor. I take off the serpentine belt and the vibration goes away, only change was the shotgun so that's my variable that's causing this vibration.

Edit - FIXED!! I don't know what it was, but it has to be with the belt/tensioner/etc setup. Ripped it all out and reinstalled and the buzz is gone.

 

[martymil]

Lol the 1m has the m3 diff but not changing to solid bushing.

Too much vibration and nvh.

Need a diff brace.

Did you replace your pump or is it old ?

 

[dyezak]

Lol the 1m has the m3 diff but not changing to solid bushing.

Too much vibration and nvh.

Need a diff brace.

Did you replace your pump or is it old ?

There is 0 additional NVH going to solid diff mounts. The subframe bolts to the chassis on 4 soft squishy rubber mounts, if you put solid bushings there you WILL get increased NVH. But going solid on the diff was imperceptible to me. The subframe bushings kept the NVH great.

EDIT - This is coming from someone who just ripped out and reinstalled a VTT shotgun twice because I was fighting an NVH issue that I couldn't stand. A slight buzz at 25-3500rpm. I also hate the in-floor subs because my left foot feels a slight buzz from the bass when I play the stereo.

 

[martymil]

Your a champ this is exactly what I needed to hear.

Placed an order for the bimmerworld ones as they where on
special and decently priced shipping

 

[fmorelli]

I also hate the in-floor subs because my left foot feels a slight buzz from the bass when I play the stereo.

The factory under seat woofers are junk. I wouldn't be surprised if you replace them with some quality speakers that buzz might just disappear. It's too bad the car is not a Mustang. That would add 20 horsepower.

Filippo

 

[doublespaces]

Reminds me. I've had the upgraded sws-8 woofers for about a year and haven't installed them.

 

[martymil]

This surprises me because the 1m woofers are surprisingly good and I had no issues with mine

Then again I never crank my stereo up. LOL

 

[fmorelli]

This surprises me because the 1m woofers are surprisingly good and I had no issues with mineL

Well of course, you got the ///M woofers lol

Filippo

 

[martymil]

Ha Ha funny lol

Nah but seriously its the same speaker but the M has the additional amplifier in your drivers left rear quarter panel so it might not be the speaker itself,

When i had my 135 I remember the woofers being weak so I added a 10" woofer in the boot to compensate, i added tweeters
f & r as it never had any and with a bit of fiddling of the equaliser it sounded ten times better.

But lets stay on topic in this thread got my new 93 tune for the double barrel and the new gc's 2.0

Its going to be very interesting how these compare to the orginal rb's.

When you look at the housing they are substantially bigger where they need to be

When you have them side by side that's when you see the size difference.

As far as i know these are the first ones in oz, i swore I wouldn't do firsts again but here we go.

Let the fun times begin.

 

[martymil]

There is 0 additional NVH going to solid diff mounts. The subframe bolts to the chassis on 4 soft squishy rubber mounts, if you put solid bushings there you WILL get increased NVH. But going solid on the diff was imperceptible to me. The subframe bushings kept the NVH great.

EDIT - This is coming from someone who just ripped out and reinstalled a VTT shotgun twice because I was fighting an NVH issue that I couldn't stand. A slight buzz at 25-3500rpm. I also hate the in-floor subs because my left foot feels a slight buzz from the bass when I play the stereo.

So I installed the bushes today hell of a job btw, on a hoist with all the right tools it took around 4 to 5 hrs.

We put the bushes in the freezer overnight to make it easier to install, which helped actually.

What a difference , no more axel tramp and no nvh from the diff only bimmerworld bushes.

Thanks heaps dude.

 

[dyezak]

So I installed the bushes today hell of a job btw, on a hoist with all the right tools it took around 4 to 5 hrs.

We put the bushes in the freezer overnight to make it easier to install, which helped actually.

What a difference , no more axel tramp and no nvh from the diff only bimmerworld bushes.

Thanks heaps dude.

View attachment 14239 View attachment 14240 View attachment 14241

 

[martymil]

So now its been over a year and a half and around 15 to 20k and the pumps are holding up just fine, everything is working properly as it should.

I'll keep updating you guys every so often but so far the setup has been flawless and can easily say there is nothing to worry about overdriving the pump.

I was happy if the pump only lasted a year but it seems it surpassed my expectations.

Big thumbs up to the VTT team, you guys rock.

 

[MoreBoost]

Funny. I've had a diff brace for years. GC turbos at 27 psi and I've never had any issues with my diff luckily.

 

[martymil]

The di pump has a direct relation to the kit as its being over driven.

All im saying is that people should not be worried over the longevity of the pump as it's no longer in question as it seems that after almost 2 years its still going very strong without any issues due to being over driven.

But I'm glad the diff is holding the power the gc's are making, you have a nice strong brace, well done.

 

[Bnks334]

So I installed the bushes today hell of a job btw, on a hoist with all the right tools it took around 4 to 5 hrs.

We put the bushes in the freezer overnight to make it easier to install, which helped actually.

What a difference , no more axel tramp and no nvh from the diff only bimmerworld bushes.

Thanks heaps dude.

View attachment 14239View attachment 14240View attachment 14241

How have your diff bolts been holding up?

I kept snapping diff bolts. Tried grade 12.9 bolts and still no good. Moving from poly street to poly race (stiffer) bushings only made the bolts break faster. Stock rubber bushings did a great job at preventing shock load to the bolts but obviously allowed the diff to wander around too much. The stiffness of the poly was transferring more load to the bolt. I ended up having to drill out the holes and using M14 bolts. No issues since.

 

[martymil]

Since going to the bimmerworld bushes and using the 12.9 allen head bolts I haven't broken a bolt since.

A tiny bit of NVH can be felt and heard but only if you really listen for it and after a while you just don't notice it.

I'm really pedantic when it comes to noises and do not/can not tolerate much, I would rather break diff bolts than
have to put up with any excessive noise.

https://www.bimmerworld.com/E8X-E9X-M3-1M-Solid-Aluminum-Differential-Mount-Set.html

 

[BigMario]

Hi
I bought hpfp s55
who knows how to connect , second pump for dme 1726 n55?
Thanks

 

[martymil]

So over 2.5 years after install and over 20k miles and pumps are still holding up fine, no nvh and smooth as a kitten.

@V8bait was critical in dialling in the the db shotgun and Gc's 2.0 turbo on 93.

E was later added to make e15 to supress a little knock but can be driven safely on straight 93, fuel demands on the system are negligible
when such little E is added but it makes the logs look pretty and clean.

Been running new injectors, two new hpfp's and a single bucketless 450 and they all have been holding up nicely running over 600 - 630 hp since install.

This setup has been absolutely bullet proof and longevity concerns have been nulled.

This is my summer tune snapshot in action with csv file underneath.

 

[martymil]

Its been three years since I installed my double barrel and I wanted to keep sharing my experience, how the kit is performing and holding up in my car.

So we decided to drop the motor 2 years after rebuild just to check it over as I had a small leak from the back of the head.

We found I stretched one of the rear head bolts ever so slightly, it only just weeps and leaves a small puddle under the car size of a dinner plate overnight.

But this is not about my car and what we are going to do with it as thats going to be another thread altogether.

So for those that think that double barrels fail, they don't and you don't have to worry about failures.

Proof is in the pudding so this is my three year old kit for you to ponder over and its perfect with no signs of any issues what so ever.