VRSF downpipes worth it or not...?

[john-e89]

This 365bhp mapped 35i is a pretty lively I have to say...! So far it has the map, M3 front control arms, H&R front anti roll bar, new yet standard springs and struts and M4 reps with new Eagle F1’s. To move it further on I’ve ordered KWV3’s, a full Eisenmann race cat back exhaust, and a Quaife diff as quite honestly it’s a bit of a handful in the wet especially, it grabs the rear offloaded wheels and tries to have you into the trees, torque steers from the rear as well in the dry all due to the crap OEM open diff so a Quaife should reign it in as well as the KW’s. So when they’re all on and hopefully a sorted chassis we can go after engine tuning a little more, I’ll be walnut blasting it myself, so next is improved breathing, are the VRSF downpipes worth putting on for better spool up etc, or any other make...? I don’t want monkey metal ones that crack, just good quality items, buy right buy once is my motto. Also a bigger intercooler as I might crank it up to 400bhp once the chassis is done.

Any thoughts please..?

[Pbondar]

I’m not an N54 specialist..

I think the diff is a good move..was a major benefit on my N20 even before the latest mods...in the wet it transforms the ability to press on...

I have the VSRF de-cat pipe on my N20...build quality is very good..

Given the N54 uses two light pressure turbos I’m not sure how much benefit you would get in spool up time..

In the UK the improved intercooler is mostly in ‘because you can’ category..but since you are already in that territory why not..

The intercooler shows its benefits under repeated and sustained full throttle charges especially in high ambient temps..

How hot it gets here and how often you can repeatedly hold the throttle wide open are mute points..

[Jollyjoiner]

I'm interested to see how the diff mod goes as like you say they are a tad lively in the wet and dry sometimes. With the 365bhp mine has now, in the dry and launch control it will just want to spin you sideways towards the weeds lol

[john-e89]

I’m not an N54 specialist..

I think the diff is a good move..was a major benefit on my N20 even before the latest mods...in the wet it transforms the ability to press on...

I have the VSRF de-cat pipe on my N20...build quality is very good..

Given the N54 uses two light pressure turbos I’m not sure how much benefit you would get in spool up time..

In the UK the improved intercooler is mostly in ‘because you can’ category..but since you are already in that territory why not..

The intercooler shows its benefits under repeated and sustained full throttle charges especially in high ambient temps..

How hot it gets here and how often you can repeatedly hold the throttle wide open are mute points..

‘Because I can territory‘....?? If something isn’t going to improve the car it won’t get bolted on, I’m not wasting money on it so I’ll ignore that presumption dig....

Anyway, the reason for a bigger intercooler is in this case more to do with not wanting to create possible back pressure for the turbos due to a flow restriction if i go to 400+bhp, I haven’t a clue if the standard cooler could cope so I’d rather make sure we don’t have any potential breathing issues by erring on the side of caution, I’m a firm believer in over engineering. Thanks for the reply on the VRSF, just what I wanted, an opinion from experience.

[john-e89]

I'm interested to see how the diff mod goes as like you say they are a tad lively in the wet and dry sometimes. With the 365bhp mine has now, in the dry and launch control it will just want to spin you sideways towards the weeds lol

Tyre pressures have a big influence too Nige, Sam had them too low as he liked the comfort, I went a tad too high and it was, frankly, lethal in the wet, it’s much improved but still nothing like the M for control, Birds are sending me a complete unit to bolt up as they won’t do an exchange on diffs with over 60k miles on them.

[bob20124]

Congrats on mods. Consider a better intercooler before DP (exhaust should make quite a difference). Best mod for the increased power handling is the LSD. Consider a metal charge pipe with either a BOV or better quality diverter valves (oems tend to leak and plastic charge pipe can fail over time with higher pressure). I'm still catted for inspection purposes (stateside). most estimates I've seen on DP is 20-30 HP increase. Another change which made quite a difference in handling was increasing tire width (245 40 18 front, 275 35 18 rear PS4S). Jury is out on OCCs for another 30,000mi.

Please update thread as you go.

[john-e89]

Congrats on mods. Consider a better intercooler before DP ( exhaust should make quite a difference). Best mod for the increased power handling is the LSD. Consider a metal charge pipe with either a BOV or better quality diverter valves (oems tend to leak and plastic charge pipe can fail over time with higher pressure). I'm still catted for inspection purposes (stateside). most estimates I've seen on DP is 20-30 HP increase. Another change which made quite a difference in handling was increasing tire width (245 40 18 front, 275 35 18 rear PS4S). Jury is out on OCCs for another 30,000mi.

Please update thread as you go.

Cheers Bob,

Scratching my head on OCC tbh....

I’m on wider new rubber so all good there. Metal charge pipe with a BOV is a thought, I’m sure it could be diverted to the air box so I don’t get the silly pssssssssssshhhhhh wump...

[Jollyjoiner]

I'm interested to see how the diff mod goes as like you say they are a tad lively in the wet and dry sometimes. With the 365bhp mine has now, in the dry and launch control it will just want to spin you sideways towards the weeds lol

Tyre pressures have a big influence too Nige, Sam had them too low as he liked the comfort, I went a tad too high and it was, frankly, lethal in the wet, it’s much improved but still nothing like the M for control, Birds are sending me a complete unit to bolt up as they won’t do an exchange on diffs with over 60k miles on them.

Can't quite remember off hand what I have my tyres set at, I think 36 psi springs to mind.
So Birds do a complete diff already set up do they ? as well as the diff internals if your wanting to use your existing diff housing ? I believe they can take a bit of setting up so guessing a complete unit including housing then that they are already set up.

[bob20124]

There are good high quality diverter valves available (change when they start going bad). Decided on OCC after walnut blasting. Don't know how effective yet. Running high side for 4 years and added low side 7mo. ago. One major item I recently upgraded was the clutch. It could not handle torque till fully engaged (I'm manual 6spd).

[Pbondar]

I’m not an N54 specialist..

I think the diff is a good move..was a major benefit on my N20 even before the latest mods...in the wet it transforms the ability to press on...

I have the VSRF de-cat pipe on my N20...build quality is very good..

Given the N54 uses two light pressure turbos I’m not sure how much benefit you would get in spool up time..

In the UK the improved intercooler is mostly in ‘because you can’ category..but since you are already in that territory why not..

The intercooler shows its benefits under repeated and sustained full throttle charges especially in high ambient temps..

How hot it gets here and how often you can repeatedly hold the throttle wide open are mute points..

‘Because I can territory‘....?? If something isn’t going to improve the car it won’t get bolted on, I’m not wasting money on it so I’ll ignore that presumption dig....

Anyway, the reason for a bigger intercooler is in this case more to do with not wanting to create possible back pressure for the turbos due to a flow restriction if i go to 400+bhp, I haven’t a clue if the standard cooler could cope so I’d rather make sure we don’t have any potential breathing issues by erring on the side of caution, I’m a firm believer in over engineering. Thanks for the reply on the VRSF, just what I wanted, an opinion from experience.

I’m sorry you saw my comment as a dig..

The primary purpose of the intercooler is to reduce charge temperatures post turbo pre engine...

It’s a complex issue as large intercoolers increase lag which is contrary to your statement about faster spool times, the more volume in the inlet area the ore the turbo has to puff to fill the volume at the requisite pressure..

Also there are two types of construction of IC, one aimed at the sprint type guys and one aimed at the race type guys..

The flow rate through the IC or looking at it the pressure drop for flow through is a key parameter...

Wagner/VSRF and others have slanging matches as to whose has the best flow / least pressure drop..

Decent IC are pretty expensive ..according to my tuning guys the Chinese copies are dreadful on flow / pressure drop

Over-engineering is laudable but as I say ironically a much bigger IC may be counterproductive in terms of roll on / pick up ...

The N54 makes so much power it’s a bit academic IMHO...

One of the big advantages of these modern turbos is the massive low end torque..it would be a pity to lose that to gain a little at what would be an academic top end, IMHO...

Having gone for a bigger turbo and Wagner IC, that loss of low end torque is noticeable if you just want to gently potter part of the time..if it’s full bore most if the time then it doesn’t matter..

The Quaife on the 35 needs a welded crown wheel mount cutting to fit the LSD so it’s a bigger job than on the E85 and E89 N20..that maybe part of the ‘whole part supply’ issue as well..

[john-e89]

I’m not an N54 specialist..

I think the diff is a good move..was a major benefit on my N20 even before the latest mods...in the wet it transforms the ability to press on...

I have the VSRF de-cat pipe on my N20...build quality is very good..

Given the N54 uses two light pressure turbos I’m not sure how much benefit you would get in spool up time..

In the UK the improved intercooler is mostly in ‘because you can’ category..but since you are already in that territory why not..

The intercooler shows its benefits under repeated and sustained full throttle charges especially in high ambient temps..

How hot it gets here and how often you can repeatedly hold the throttle wide open are mute points..

‘Because I can territory‘....?? If something isn’t going to improve the car it won’t get bolted on, I’m not wasting money on it so I’ll ignore that presumption dig....

Anyway, the reason for a bigger intercooler is in this case more to do with not wanting to create possible back pressure for the turbos due to a flow restriction if i go to 400+bhp, I haven’t a clue if the standard cooler could cope so I’d rather make sure we don’t have any potential breathing issues by erring on the side of caution, I’m a firm believer in over engineering. Thanks for the reply on the VRSF, just what I wanted, an opinion from experience.

I’m sorry you saw my comment as a dig..

The primary purpose of the intercooler is to reduce charge temperatures post turbo pre engine...

It’s a complex issue as large intercoolers increase lag which is contrary to your statement about faster spool times, the more volume in the inlet area the ore the turbo has to puff to fill the volume at the requisite pressure..

Also there are two types of construction of IC, one aimed at the sprint type guys and one aimed at the race type guys..

The flow rate through the IC or looking at it the pressure drop for flow through is a key parameter...

Wagner/VSRF and others have slanging matches as to whose has the best flow / least pressure drop..

Decent IC are pretty expensive ..according to my tuning guys the Chinese copies are dreadful on flow / pressure drop

Over-engineering is laudable but as I say ironically a much bigger IC may be counterproductive in terms of roll on / pick up ...

The N54 makes so much power it’s a bit academic IMHO...

One of the big advantages of these modern turbos is the massive low end torque..it would be a pity to lose that to gain a little at what would be an academic top end, IMHO...

Having gone for a bigger turbo and Wagner IC, that loss of low end torque is noticeable if you just want to gently potter part of the time..if it’s full bore most if the time then it doesn’t matter..

The Quaife on the 35 needs a welded crown wheel mount cutting to fit the LSD so it’s a bigger job than on the E85 and E89 N20..that maybe part of the ‘whole part supply’ issue as well..

I’m more than aware the purpose of an intercooler. What I’m potentially asking of the standard unit is at least another third on top of its OEM boost pressures, that’s a fair amount, and so far neither of us know if the OEM unit can take another 100bhp worth of boost without creating back pressure. Given that manufacturers usually build to the lowest possible denominator I’d have a guess it couldn’t 100%, so unless I can get flow rates of a 400+ tune along with the maximum pressure the standard unit can take I’ll go with a bigger unit as they’re not THAT much bigger, I’ve no issues with pre detonation due to heat being in the UK but I do have reservations regarding possible strangulation. A slight drop in power due to a slightly too large a cooler is preferable to a loss due to a too small a unit. I don’t know if there is a straight answer of either scenario hence my thinking.

[sunnydays]

are the VRSF downpipes worth putting on for better spool up etc, or any other make...? I don’t want monkey metal ones that crack, just good quality items, buy right buy once is my motto. Also a bigger intercooler as I might crank it up to 400bhp once the chassis is done.

Any thoughts please..?

Yes, The VSRF downpipes are good quality and are worth having. Spool time is decreased and turbo noise is lovely. VRSF is rock solid and very well reviewed, they fit perfectly. If you want to masturbate over "perfect" welds then go buy wagner. Darren Woods fitted mine in 3 hours flat. Should also scrape through an MOT with the DP's as the secondary cats are still in place.

Intercooler is worth having as your IAT's will be shooting up. Once again VRSF are solid in this department, I was going to purchase the VRSF Race 7.5" before I sold my car. That intercooler actually causes IAT's to decrease on a WOT pull. Great price too.

Here is an image of my DP's prior to fitting.

[john-e89]

are the VRSF downpipes worth putting on for better spool up etc, or any other make...? I don’t want monkey metal ones that crack, just good quality items, buy right buy once is my motto. Also a bigger intercooler as I might crank it up to 400bhp once the chassis is done.

Any thoughts please..?

Yes, The VSRF downpipes are good quality and are worth having. Spool time is decreased and turbo noise is lovely. VRSF is rock solid and very well reviewed, they fit perfectly. If you want to masturbate over "perfect" welds then go buy wagner. Darren Woods fitted mine in 3 hours flat. Should also scrape through an MOT with the DP's as the secondary cats are still in place.

Intercooler is worth having as your IAT's will be shooting up. Once again VRSF are solid in this department, I was going to purchase the VRSF Race 7.5" before I sold my car. That intercooler actually causes IAT's to decrease on a WOT pull. Great price too.

Here is an image of my DP's prior to fitting.

Where did you buy the VRSF gear from Sunny...? I’d fit them myself as I now have a ramp.

What are you tooling around in now btw...?

[sunnydays]

are the VRSF downpipes worth putting on for better spool up etc, or any other make...? I don’t want monkey metal ones that crack, just good quality items, buy right buy once is my motto. Also a bigger intercooler as I might crank it up to 400bhp once the chassis is done.

Any thoughts please..?

Yes, The VSRF downpipes are good quality and are worth having. Spool time is decreased and turbo noise is lovely. VRSF is rock solid and very well reviewed, they fit perfectly. If you want to masturbate over "perfect" welds then go buy wagner. Darren Woods fitted mine in 3 hours flat. Should also scrape through an MOT with the DP's as the secondary cats are still in place.

Intercooler is worth having as your IAT's will be shooting up. Once again VRSF are solid in this department, I was going to purchase the VRSF Race 7.5" before I sold my car. That intercooler actually causes IAT's to decrease on a WOT pull. Great price too.

Here is an image of my DP's prior to fitting.

Where did you buy the VRSF gear from Sunny...? I’d fit them myself as I now have a ramp.

What are you tooling around in now btw...?

I got them from ML Performance mate. Outstanding service from them consistently.
https://www.mlperformance.co.uk/product ... y-delivery
The website states they are discontinued not sure if that is the case. I have a direct line for Marshal Lee (the owner) if you want to get in touch.

Currently in a A45 AMG, had a few cars since the Z4, but feeling the urge to grab a 35is again (lol). Ideally buy my old one back. Not sure what it is about the 35is, but it is bizarrely a very hard car to replace. It does so many things right, just a fantastic combo of a car.

[john-e89]

Cheers mucker.

I agree, flawed but they have something that makes me keep wanting one too.