8 Throttle bodies vs Dual Throttle bodies, Dinan Myth? - The Unofficial BMW M5 Messageboard (m5board.com)

MIB · 26th December 2003, 03:56

Hey guys. This has bugged me for quite awhile, so I need some Tech input here.

My HSV'S (Holdens Chevys) Had single throttle bodies but you could upgrade to the Group A or Motech Dual throttle bodies.

Basically it is twin butterflys. They are at the front of the plenum where the CAI mate up.

Now I have heard Dinan say they put larger Dual throttle bodies on.

The Beast does not have Dual throttlel bodies. It looks like it does from the front. But when I took off the plenum cover, there are just two holes at the front.

Then I remembered

The beast has 8 Individual butterflys. They are directly below the velocity stack.

I'll try and organise pics later.

So if Dinan say $5K for velocity stacks (witch are similar to stck

) and larger dual throttle bodies

Are they just talking about increasing the diameter of the two holes in front.

Where is the $5K. The awesome Technic stacks are $1K. Are they charging you $4K to bore out the two holes in front? This is a Question.
I don't know. Or are they giving you 8 new throttle bodies, which I don't belive is neceassary and don't believe they are. Otherwise they would say, "8" larger throttle bodies/Butterflys.

As I said on another thread, it is no point making the holes larger unless you have the same increased diameter in the CAI. Well Congrats DINAN they did that.

So I love their increased diameter CAI and MAFS, full marks for those. But I have the trumpets for $1K, I could get the CAI and MAFS and get someone to bore out the two holes in front of the plenum for $200.

So where is the $5 K Dinan charges?

Regards MIB.

ELEVENS · 26th December 2003, 05:24

Quote:

Originally Posted by MIB

...Now I have heard Dinan say they put larger Dual throttle bodies on....So... if Dinan say $5K for velocity stacks (witch are similar to stck

) and larger dual throttle bodies ...Where is the $5K. ... Are they charging you $4K to bore out...

Hi Mark. Hope you had a great Christmas!

I think Dinan provides larger tuned, spun aluminum "trumpets" that are shaped more like the stockers and not as cool looking as yours

I don't know this for sure, but I would guess the $5k might buy eight bored-out throttle bodies (exhanged for your stock ones?), which hopefully would include new, larger butteryflies safely staked to a new shaft, riding in new bushings, with the minimum opening (gap) properly set. New bushings are important because this a wear point and any "slop" would introduce unmetered air into the motor that the computer would not know about.

Maybe someone who knows more than me about Dinan can chime in. Heck, I don't own a single Dinan piece

, but maybe someday I would like to get one of those nice Dinan shirts

Bill

jeeperjohn · 26th December 2003, 06:27

Mark and Bill,

First, MERRY CHRISTMAS!!!!

Second, The Dinan mod is what Bill said it is. You got to remember that when a guy takes a hard to replace part (uncommon or pricey) and starts machining on it, he has to throw in a some cushion in the price if he scraps the customer part during the set-up or machining. (lets face it, if you picked up your intake and saw that they had welded up a mistake and remachined it to make it fly, you might want a new replacement. Edelbrock Manifold Corp, would take manifolds that had a to have a thread insert installed and not sell them, but would sell them as seconds (stamped as seconds) to vendors at a discount for their personal vehicles. they did this to keep up thier quality image with the public) It's kind of like any other business, it's not the cost of the job that goes smooth, but the development and risk factors when working on it, and just how many M5 guys are there that are going to buy it.

It always amazes me how much horsepower a guy can get from Chevy TPI's with the dual throttle plates (52mm x2) without getting real exotic compared to something like the manifold on the M5. Don't misunderstand me, the M5 has pretty scienced out intake system that does everything possible for a production car. Bill can probably vouch for the Chevys with his past experience with racing a TPI.

I think Dinan has to charge the prices to recover the development costs and the reality of how many people are going to buy the product.

John

MIB · 26th December 2003, 07:11

From there website.

The High Flow Throttle Bodies and tuned Velocity Stacks further improve intake air-flow for additional horsepower and torque gains, as well as providing quicker throttle response. The M5's eight throttle bodies have been bored for a larger internal diameter increasing air-flow. The factory Velocity Stacks are replaced with larger-diameter, spun aluminum units that have been carefully tuned for improved high rpm "breathing". The internal surfaces have also been polished for optimum flow and resulting power gains. Stage 5 Performance Engine Software is required, as well as the Cold Air Intake, High Flow Air Flow Meters, Free Flow Exhaust and Header System. The combination produces 470 horsepower and 419 lb/ft torque, for an incomparable M5 driving experience.

O.K. At least they are boring all eight and not just the front two holes.

470Hp, I'd like to see that.

Ewwwwhh.

Vadim-SoCal · 26th December 2003, 09:07

Individual Throttle Bodies, also commonly called Individual Runner (IR) Intake, have been M-division's signature pretty much from day one.

There are pros and cons in using IR manifolds:

Pros:

1. Sharper throttle response.

2. Better tunability by adjusting trumpets length. The longer the trumpet the lower, in rpm, TQ peak is going to be, the shorter the trumpet the higher TQ peak is going to be.

3. Can be used as marketing tool. F1 engine all use IR manifolds.

Cons:

1. Cost - between linkage and extra throttle bodies, can be significantly higher. Thus reserved by BMW for their top of the line models.

2. A properly tuned "common plenum" manifold still can offer broader TQ curve than even the best IR set-up, raising questions about IR cost feasibility.

What this all means on S62 is that great HP numbers can be achived by tuning headers, cams and trumpets to produce power in the same range, thus greatly elevating TQ curve.

On a stock M5, simply installing shorter trumpets results in 10RWHP gain from 5500 - 7000 rpms. However, there is a loss of 10-15 lb.ft. of TQ from idle till 5500 rpms. Car feels faster since TQ drop at higher rpms is not as great as with stock trumpets.

They need to be combined with shorter gearing, headers, mild cams and proper software tuning to work together.

ELEVENS · 26th December 2003, 14:25

Quote:

Originally Posted by vadim @ evosport

...On a stock M5, simply installing shorter trumpets results in 10RWHP gain from 5500 - 7000 rpms. However, there is a loss of 10-15 lb.ft. of TQ from idle till 5500 rpms. Car feels faster since TQ drop at higher rpms is not as great as with stock trumpets.

They need to be combined with shorter gearing, headers, mild cams and proper software tuning to work together.

That's useful info Vadim - thanks. Looks like what we have is the old "rob Peter to pay Paul" or the "no such thing as a free lunch" addage. But for those willing to give up a little torque, the short stacks are another dime (10HP) up the horsepower ladder.

A lot can be said about mass production and supply-and-demand. On a Chevy, you can buy a brand new, large-bore throttle body, machined entirely from a billet aluminum block for around $500 (Lingenfelter). Bored-out ones are around $250 (TPiS). Likewise, stainless steel headers are 1/8 the cost of the Dinan headers.

Bill

MIB · 26th December 2003, 17:33

Quote:

Originally Posted by vadim @ evosport

Individual Throttle Bodies, also commonly called Individual Runner (IR) Intake, have been M-division's signature pretty much from day one.

On a stock M5, simply installing shorter trumpets results in 10RWHP gain from 5500 - 7000 rpms. However, there is a loss of 10-15 lb.ft. of TQ from idle till 5500 rpms. Car feels faster since TQ drop at higher rpms is not as great as with stock trumpets.

They need to be combined with shorter gearing, headers, mild cams and proper software tuning to work together.

Hey Vadim,
Thanks for the explaination.

As Yoda is Hardly a stock beast

That may account for why I don't really feel any loss down low, but I definitely feel the extra kick up high. I always felt my car lacked a little after 5,000. It would still rev out, but it didn't used to pull as hard as down low. Its like the stacks filled a gap. I may have lost a touch under 2,000 rpm but With my clutch and driving style, the Beast is rearly below 2,000. It will lite the tyres on demand.

The Iats made the car nice down low as well. I have your pullies and the Plasma coils, as well.

I think Headers & Cats will be next.