E36 328i throttle body conversion....
Discussion
dell.k said:
Yes, the standard airbox is restrictive in it's design. A new panel filter will impove things a tiny bit, but hardly anything(airflow goes forwards and backwards and just take a look at the size of the inlet snorkel feeding the airbox from between the headlight and rad.
Cheers. I've had a good look at the whole intake thing and it seems very elaborately engineered (and therefore, costly!!) and that's why I didn't want to mess with it too much, as my thinking was that it had to be there for a good reason!!
Standard airbox is not created for maximum performance. It is a balance between that, the fact that one airbox fitted all models (cost thing) and lastly, but importantly, it has to silence intake roar.
Trust me on this, the kit you see fitted to my 328i, on it's own, releases 10~12 proven BHP on a roling road when tested back to back with the standard afair. Throttle response is improved across the rev range.
Sound wise, when driving normally, you cannot tell the difference. When giving it some, it sounds simply awesome.
Check my dyno plots and you can see it's not exactly performing badly for a 100,000 mile old M52 lump.
>> Edited by dell.k on Tuesday 25th April 16:29
Trust me on this, the kit you see fitted to my 328i, on it's own, releases 10~12 proven BHP on a roling road when tested back to back with the standard afair. Throttle response is improved across the rev range.
Sound wise, when driving normally, you cannot tell the difference. When giving it some, it sounds simply awesome.
Check my dyno plots and you can see it's not exactly performing badly for a 100,000 mile old M52 lump.
>> Edited by dell.k on Tuesday 25th April 16:29
xm5er said:
Maquis Rex, any professional comment on the baffle picture?
I can only theorise why the restrictor is as elaborately shaped as it is. It is definately designed to restrict to keep the performance down, although the claims made on the dyno run do not match data I've seen: the restrictor alone isn't the only way that performance was restricted on this car, the inlet manifold is common with the period 320i and therefore undersized and the intake cam profile is only a 228 period cam (even the exhaust period is 244!)
I think the retrictor is shaped that way to perhaps act as a quarter wave resonator and to target an NVH "boom" in the engine rev range. NVH booms may seem unpleasant to alot of Lexus drivers but most enthusiasts like them so I wouldn't worry.
The part also seems to have a bell mouth or entry trumpet, which would suggest it was there to smooth out flow into the air box, this is somewhat odd if we think the purpose of the part is to act as a restrictor: why would you be trying to smooth out the flow and lower the losses into the airbox when you're trying to also restrict it!
No, I'll go with the NVH theory.
As for claims of "throttle response improvement" can we please keep the trashy non-technical journalism attempts down to a minimum?
Lower intake losses won't improve "throttle response". "Throttle response" is a measurable quantity and not a semantic.
To improve thorttle response you can lower the engines reciprocating mass,
lower the rotational inertia (ie perhaps use a lighted flywheel)
Move the positioning of the throttle butter fly closer to the inlet valves (like using port throttles a la M3)
Or reduce the volume of the plenum itself (but this can impact actual performance.
These are just a few ways.
Marquis_Rex said:
Maquis Rex, any professional comment on the baffle picture?
I can only theorise why the restrictor is as elaborately shaped as it is. It is definately designed to restrict to keep the performance down, although the claims made on the dyno run do not match data I've seen: the restrictor alone isn't the only way that performance was restricted on this car, the inlet manifold is common with the period 320i and therefore undersized and the intake cam profile is only a 228 period cam (even the exhaust period is 244!)
I think the retrictor is shaped that way to perhaps act as a quarter wave resonator and to target an NVH "boom" in the engine rev range. NVH booms may seem unpleasant to alot of Lexus drivers but most enthusiasts like them so I wouldn't worry.
The part also seems to have a bell mouth or entry trumpet, which would suggest it was there to smooth out flow into the air box, this is somewhat odd if we think the purpose of the part is to act as a restrictor: why would you be trying to smooth out the flow and lower the losses into the airbox when you're trying to also restrict it!
No, I'll go with the NVH theory.
As for claims of "throttle response improvement" can we please keep the trashy non-technical journalism attempts down to a minimum?
Lower intake losses won't improve "throttle response". "Throttle response" is a measurable quantity and not a semantic.
To improve thorttle response you can lower the engines reciprocating mass,
lower the rotational inertia (ie perhaps use a lighted flywheel)
Move the positioning of the throttle butter fly closer to the inlet valves (like using port throttles a la M3)
Or reduce the volume of the plenum itself (but this can impact actual performance.
These are just a few ways.
Thanks for coming back on this.
I must admit it was the bell mouth shape which caused me to think that this was a mighty strange "restrictor". I still cant feel any discernable difference in performance or noise TBH but I have noticed a bit more snatch (must be the sunny weather) at low revs, however as I mentioned I corrected a large air leak at the same time so its very difficult to tell. I'm going to bung it back in to check.
WRT "throttle response" I think people are talking about feeling more engine torque when its booted rather than quicker engine pick up, which would make sense.
Beyond the intake and exhaust mods mentioned in the thread, what else can you do to the 2.8 lump, has anybody bunged throttle bodies on (M3 ones perhaps) or changed the inlet cam. At what point do you stop with the 2.8 and buy an M3, the fact that the engine is considerably lighter is what makes it attractive to me.
xm5er said:
Maquis Rex, any professional comment on the baffle picture?
I can only theorise why the restrictor is as elaborately shaped as it is. It is definately designed to restrict to keep the performance down, although the claims made on the dyno run do not match data I've seen: the restrictor alone isn't the only way that performance was restricted on this car, the inlet manifold is common with the period 320i and therefore undersized and the intake cam profile is only a 228 period cam (even the exhaust period is 244!)
I think the retrictor is shaped that way to perhaps act as a quarter wave resonator and to target an NVH "boom" in the engine rev range. NVH booms may seem unpleasant to alot of Lexus drivers but most enthusiasts like them so I wouldn't worry.
The part also seems to have a bell mouth or entry trumpet, which would suggest it was there to smooth out flow into the air box, this is somewhat odd if we think the purpose of the part is to act as a restrictor: why would you be trying to smooth out the flow and lower the losses into the airbox when you're trying to also restrict it!
No, I'll go with the NVH theory.
As for claims of "throttle response improvement" can we please keep the trashy non-technical journalism attempts down to a minimum?
Lower intake losses won't improve "throttle response". "Throttle response" is a measurable quantity and not a semantic.
To improve thorttle response you can lower the engines reciprocating mass,
lower the rotational inertia (ie perhaps use a lighted flywheel)
Move the positioning of the throttle butter fly closer to the inlet valves (like using port throttles a la M3)
Or reduce the volume of the plenum itself (but this can impact actual performance.
These are just a few ways.
Thanks for coming back on this.
I must admit it was the bell mouth shape which caused me to think that this was a mighty strange "restrictor". I still cant feel any discernable difference in performance or noise TBH but I have noticed a bit more snatch (must be the sunny weather) at low revs, however as I mentioned I corrected a large air leak at the same time so its very difficult to tell. I'm going to bung it back in to check.
WRT "throttle response" I think people are talking about feeling more engine torque when its booted rather than quicker engine pick up, which would make sense.
Beyond the intake and exhaust mods mentioned in the thread, what else can you do to the 2.8 lump, has anybody bunged throttle bodies on (M3 ones perhaps) or changed the inlet cam. At what point do you stop with the 2.8 and buy an M3, the fact that the engine is considerably lighter is what makes it attractive to me.
I won't answer your performance improvements questions on the M50/M52 YET, however, your line of reasoning got me thinking!
You mentioned low end "snatch"- where is the MAF sensor on a 328i? Is it very near the airbox?
how far?
I ask these because I know on 928 Porsches, folks have removed the gause mesh like "flow straighteners" on the hotwire MAF sensors to reduce pressure drop across this component. This has been known to cause low speed flow measurement problems- this can manifest itself as low speed "snatching" or "bucking". So I was wondering whether the bell mouth was there to act as a flow straightener. I seriously doubt the MAF sensor is close enough to the air box (must be about 100-200 mm near to it to have an effect, otherwise the flow would naturally just recover) but I thought I would ask.
I was indeed referring to the torque increase when derestricted, which would give the impression of throttle responsiveness being improved. Removing the viscous fan and replacing with a thermostatically controlled electric one and fitting UUC lightweight underdrive pulleys will also improve this by removing parasitic drag. Remapping helps too.
Throttle bodies, say from an Evo, are virtually impossible to retro fit. The oil filter housing for one gets in the way. Big shame as the gains would be good (with a hairy cam).
Dbilas boddies would work a treat, as the kit is made for the 328 specifically, but expensive!
With regard to cams, a set of second hand US M3 cams (S50) work very well. US M3's are reworked M50's/M52's and as such are much closer to the UK 325/328 than the UK E36 M3's (S50/S52). Look at about 7 BHP from this + more torque.
They don't need to be US M3 cams, it's one option, the other is a set of new Schrick cams (which use the same profile as the US M3 items by the way) but they will cost a lot more!!
Hope this helps a little.
>> Edited by dell.k on Wednesday 26th April 11:22
Throttle bodies, say from an Evo, are virtually impossible to retro fit. The oil filter housing for one gets in the way. Big shame as the gains would be good (with a hairy cam).
Dbilas boddies would work a treat, as the kit is made for the 328 specifically, but expensive!
With regard to cams, a set of second hand US M3 cams (S50) work very well. US M3's are reworked M50's/M52's and as such are much closer to the UK 325/328 than the UK E36 M3's (S50/S52). Look at about 7 BHP from this + more torque.
They don't need to be US M3 cams, it's one option, the other is a set of new Schrick cams (which use the same profile as the US M3 items by the way) but they will cost a lot more!!
Hope this helps a little.
>> Edited by dell.k on Wednesday 26th April 11:22
The reason why the breathing of the 328i engine was artificially restricted, by the way, is simple - back then 193 PS was the maximum allowed within a certain category in German insurance classification. It comes as no surprise then, that the contemprary Audi 2,8l V6 came in at exactly 193 PS also...
900T-R said:
The reason why the breathing of the 328i engine was artificially restricted, by the way, is simple - back then 193 PS was the maximum allowed within a certain category in German insurance classification. It comes as no surprise then, that the contemprary Audi 2,8l V6 came in at exactly 193 PS also...
We know that and dont doubt it.
BTW Cheers dell.k for the response.
I've been having a shufty round www.realoem.com/bmw and if you compare the euro 328 with the US M52 based M3, the part numbers for throttle body, airbox assy, and intake manifold are all the same (likewise the m50 based M3 and the 325). So where do the extra ponies (260bhp IIRC for US m3) come from?
Curiouser and curiouser!
dell.k said:
From 3 Litres maybe - although I am surprised that the S50 uses the same manifold as the M52! It just does not flow enough.
>> Edited by dell.k on Wednesday 26th April 14:12
According to that website the US M3 uses a M50 then M52 engine, could be wrong as I'd be rather surprised too.
Going back to your earlier reply, the most power that you are likely to get out of the 328 is about 250bhp before you reach the "might as well buy an M3" cost stage. Not bad considering that it weighs in at about 135kg less (according to the manual). Only 35kg less than an M3 gt though.
Dunk76 said:
Marquis_Rex said:
the Lamda sensors will ensure the AFR is kept correct.
Not above 3500rpm it won't
Actually it will during closed loop mode regardless of rpm. I don't know what the relevance of 3500 rpm is or where you got that number from.
On the BMW 328i about 78% of the engine-load speed map is stoichiometrically calibrated- i.e running in "closed loop" control mode". The enrichment borderline goes from about 1000 rpm /greater than 8 bar BMEP- progressively getting lower in load until about 6000 rpm/5 bar BMEP.
Richest AFR ratio it runs is about 0.83 at about 6 grand/full load.
The enrichment is calibrated to decrease exhaust temperature to avoid catalyst damage.
If the restriction is removed and the general engine air flow is increased- if the air flow becomes greater than the "clamp" or maximum allowable value of the MAF sensor then the engine could run lean. I don't know what the limit of the MAF sensor is or if indeed it would be reached.
Well that was my point - during closed loops all's good and well.
Every M52 I've seen on the dyno run goes to Open Loop at 3500rpm at WOT.
My point is that relying solely on closed loop to sort the fuelling out isn't the best way, IMHO.
However, I suspect that the limited increase in airflow allowed by the BBTB conversion would still be within AMM parameters to measure.
Worth noting the injector flow limitations though, I know people that have hit fuelling issues with a BBTB, Cams, Remap - even with an adjustable FPR.
Also worth considering the state of the AMM - the Alpina on the Dyno at 60K miles proved to be interesting - the fuelling plot showed nice and lean on closed loop, then a jump to enrichment as it when Open. The AMM was flakey though - the Open Loop fuelling plot resembling a seismagraph during a fairly serious earthquake.
Every M52 I've seen on the dyno run goes to Open Loop at 3500rpm at WOT.
My point is that relying solely on closed loop to sort the fuelling out isn't the best way, IMHO.
However, I suspect that the limited increase in airflow allowed by the BBTB conversion would still be within AMM parameters to measure.
Worth noting the injector flow limitations though, I know people that have hit fuelling issues with a BBTB, Cams, Remap - even with an adjustable FPR.
Also worth considering the state of the AMM - the Alpina on the Dyno at 60K miles proved to be interesting - the fuelling plot showed nice and lean on closed loop, then a jump to enrichment as it when Open. The AMM was flakey though - the Open Loop fuelling plot resembling a seismagraph during a fairly serious earthquake.
Edited by Dunk76 on Monday 16th April 09:33
se6b said:
OK...spoke too soon. Now I've managed to get the airfilter out. Wow that was a tight fit!!! I've removed part of the intake, which just slid out the front. I'm guessing this is what you were referring to? It looks like a squashed cylindrical tube about six inches long?
Do you have to unbolt and remove the entire air filter housing to remove the restrictor, or can you reach into the housing and somehow unclip it? I can see what I need to remove but cannot for the life of me work out how the get the restrictor out of the housing.
zoidberg said:
se6b said:
OK...spoke too soon. Now I've managed to get the airfilter out. Wow that was a tight fit!!! I've removed part of the intake, which just slid out the front. I'm guessing this is what you were referring to? It looks like a squashed cylindrical tube about six inches long?
Do you have to unbolt and remove the entire air filter housing to remove the restrictor, or can you reach into the housing and somehow unclip it? I can see what I need to remove but cannot for the life of me work out how the get the restrictor out of the housing.
I was in the same position!
Best thing to do is to take the whole filter out (disconnect the front intake, unscrew the screws to the right hand side of the filter housing and pull!)
The funnel should then just slip out of the front of the airbox.
HTH
Anybody know what the relative difference in performance gain is between the throttle body upgrade compared to changing the 328 manifold to a 325 manifold. Looking at e36coupe.com, the increase in the throttle body diameter seems to be minor compared to that of the manifold.
I have removed the restictor in the air inlet and TBH the improvement wasn't even as noticeable as changing from normal Shell unleaded to V-Power. There does seem to be an increase in low frequency rumble, but that may be worn tyres.
Certainly no better at the top end.
I have removed the restictor in the air inlet and TBH the improvement wasn't even as noticeable as changing from normal Shell unleaded to V-Power. There does seem to be an increase in low frequency rumble, but that may be worn tyres.
Certainly no better at the top end. Gassing Station | BMW General | Top of Page | What's New | My Stuff