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Premium Member 2005 SLK55 AMG
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Discussion Starter #1
I have today learned from a Swedish magazine about the differences between an US built V8 and an European one. From sound they can clearly be separated. The cross plane (looking at the ends from the side - looking like a cross) is US style. The flat one (European) is some sort of R4 x 2 deviation with all ends in the same level - i.e. flat. That would explain the difference in sound.

As I understand it ours AMG:s are flat - giving a nice (but different) sound. But why the difference? What is the gain? I have searched the site... in vain.
 

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Premium Member 2005 SLK55 AMG
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Discussion Starter #2
The writer from that magazine is on some heavy medication :D
All AMGs are made in Germany
Need to fix this: it´s about the cranks in US cars like a Mustang - compared with an EU built car like the SLK AMG. Sorry about my first post beeing not clear.
 

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Premium Member 1999 SLK 5.4 M113
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All Mercedes V8's are cross-plane V8's. not flat.

A ferrari is a flat plane, and it causes the explosions to happen in an even manor hence why it sounds smoother.

A muscle car, or MOST V8's in existance fire in a more "un-balanced" sequence causing it to sound more rough/rumbly.

The new mustang coyote V8 is a flat plane, and sounds un-traditional.

advantages?? higher RPM's and smoother.
 

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Administrator 2009 SLK 55 AMG/Founding Member 2006
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You can edit your own thread :D
Use 'edit' button :D
 

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Premium Member 2005 SLK55 AMG
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625 Posts
Discussion Starter #5
All Mercedes V8's are cross-plane V8's. not flat.

A ferrari is a flat plane, and it causes the explosions to happen in an even manor hence why it sounds smoother.

A muscle car, or MOST V8's in existance fire in a more "un-balanced" sequence causing it to sound more rough/rumbly.

The new mustang coyote V8 is a flat plane, and sounds un-traditional.

advantages?? higher RPM's and smoother.
The new Mustang was the issue in the article - a flat one (and new to a US car). But what you say is an "un-balanced" in a "muscle car" needs to be explained. By random? Or such as cross plane? Trust there are an explanation.
 

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Premium Member 2005 SLK55 AMG
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Discussion Starter #6
BTW, thanks for giving me the info on that a MB AMG is with a cross plane crank. I had no idea, but from the sound I was sure it was a flat one.
 

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Premium Member 1999 SLK 5.4 M113
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The new Mustang was the issue in the article - a flat one (and new to a US car). But what you say is an "un-balanced" in a "muscle car" needs to be explained. By random? Or such as cross plane? Trust there are an explanation.
this is from my understanding and may vary among different engines and firing orders.

for example, most V8's are labeled cylinders 1-4 on the right, and 5-8 on the left, but the firing order is 1-8-4-3-6-5-7-2. so when you look at the firing order 4-3 are on the same side, but occur after each other in the firing order. same with 6-5-7. that's why it sounds so off beat.

A flat plane crank fires one cylinder per side at a time. which causes it to sound more even.
 

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The new Mustang was the issue in the article - a flat one (and new to a US car). But what you say is an "un-balanced" in a "muscle car" needs to be explained. By random? Or such as cross plane? Trust there are an explanation.
From Wikipedia (search for crankshaft):
Engine configuration[edit]
The configuration, meaning the number of pistons and their placement in relation to each other leads to straight, V or flat engines. The same basic engine block can sometimes be used with different crankshafts, however, to alter the firing order. For instance, the 90° V6 engine configuration, in older days[when?] sometimes derived by using six cylinders of a V8 engine with a 3 throw crankshaft, produces an engine with an inherent pulsation in the power flow due to the "gap" between the firing pulses alternates between short and long pauses because the 90 degree engine block does not correspond to the 120 degree spacing of the crankshaft. The same engine, however, can be made to provide evenly spaced power pulses by using a crankshaft with an individual crank throw for each cylinder, spaced so that the pistons are actually phased 120° apart, as in the GM 3800 engine. While most production V8 engines use four crank throws spaced 90° apart, high-performance V8 engines often use a "flat" crankshaft with throws spaced 180° apart, essentially resulting in two straight four engines running on a common crankcase. The difference can be heard as the flat-plane crankshafts result in the engine having a smoother, higher-pitched sound than cross-plane (for example, IRL IndyCar Series compared to NASCAR Sprint Cup Series, or a Ferrari 355 compared to a Chevrolet Corvette). This type of crankshaft was also used on early types of V8 engines. See the main article on crossplane crankshafts.
 

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Premium Member 2005 SLK55 AMG
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Discussion Starter #9
Thanks Turdo2 and Anders S SLK02. It explains a few things - but not why. The firing order makes a different sound = OK. I am with you there.

IMHO the sound of my V8 is different to a "muscle V8" - even if they are both "cross plane". But why the different firing order? It dosen´t make sense. To me, at least:|
 

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Thanks Turdo2 and Anders S SLK02. It explains a few things - but not why. The firing order makes a different sound = OK. I am with you there.

IMHO the sound of my V8 is different to a "muscle V8" - even if they are both "cross plane". But why the different firing order? It dosen´t make sense. To me, at least:|
At it again:

https://en.wikipedia.org/wiki/V8_engine , then go "crankshaft". :)
 

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Registered 2005 SLK55 AMG
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Thanks Turdo2 and Anders S SLK02. It explains a few things - but not why. The firing order makes a different sound = OK. I am with you there.

IMHO the sound of my V8 is different to a "muscle V8" - even if they are both "cross plane". But why the different firing order? It dosen´t make sense. To me, at least:|

Mostly due to the design of the exhaust system, MB incorporating a resonator box, to damp out the pulses.
 

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Premium Member 2001 SLK320/2000 SLK230
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Novi was a flat plane V8. Part of the reason few use them in a V engine is making an equal length exhaust system is a nightmare unless the exhaust ports are in the valley which is fine for a rear/mid engine but tad more difficult for a front engine RWD.

BTW the first modern 90 degree V6 to use offset crank pins was the Buick "even fire" 3.8/3800 in the mid 80s. Merc was a copycat.
 

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Registered 2005 SLK55 AMG
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this is from my understanding and may vary among different engines and firing orders.

for example, most V8's are labeled cylinders 1-4 on the right, and 5-8 on the left, but the firing order is 1-8-4-3-6-5-7-2. so when you look at the firing order 4-3 are on the same side, but occur after each other in the firing order. same with 6-5-7. that's why it sounds so off beat.

A flat plane crank fires one cylinder per side at a time. which causes it to sound more even.
GM labels driver side bank, 1-3-5-7, passenger side 2-4-6-8. Firing order is 18436572, and the crank throws are 90 degree out. This firing order was what was used on small blocks and big blocks from back in the day. The new LS (don't offer Big Blocks any longer), is double swap, 2-3, and 4-7, so new order is 18726543. Running a double swap cam in an older SB or BB chevy will net a smoother idle and slight power boost, but it hurts the "lope" that is so characteristic of big cam engines.
 

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Premium Member 2001 SLK320/2000 SLK230
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Part of the problem is that a V8 fires cyl 90 degrees apart so the valve openings overlap unless the cam is really ded. In most cases you are better off tuning an 8 as two fours to eliminate overlap (see also dual plane manifolds).

Now an (inline or even fire) six fires 120 degrees apart and with a proper header system up to about 6 grand your best scavenging is with equal length primaries, a single collector, and single exhaust pipe. At higher RPM duals are better when you consider pulse acceleration. Tune a 12 as two sixes.

Did I mention I really like OHC 6s ?

Also have this nut theory that on pump gasoline the ideal stroke is 3.25 to 3.50" (80-90mm). Square to a bit oversquare is good. Undersquare winds slow and low. Pick # of cyl to match desired displacement. If going to add boost, also need direct injection. Personally like trips or dual quads for fun cars and NA FI for everyday.

ps Buick evenfire also had a balance shaft you could replace without pulling the engine.
 

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Registered 2005 SLK55 AMG
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our 3.6L Cadillac V6, incredibly smooth idle, and will really move out when the throttle is pushed, believe it is rated at 310 HP.


Best engine I have owned was the 301.59 CID (302) offered in the 1967 to 1969 Z/28 camaro's. I had a clone (was an SS Car), with a fully built 302. Forged everything, Balanced, 2.02 heads, 13.5 to 1 CR. 4.0 inch bore, 3.0 inch stroke. With extra springs between the bottom of the heads to the solid roller lifter body (rev kit), that engine would pull Hard to 9500 rpm. I've seen 11,000 on the tack when I missed a gear, and it still held together. Now, that doesn't hold a candle to a REAL F1 engine that runs to 18 or 19K all race long.
 

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Premium Member 2001 SLK320/2000 SLK230
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Z28 engine (originally RPOs Z 281, 282, 283, and 284 - Z28 did not appear until '68, 67's had no insignia.) was a 283 crank in a 327 block. Purpose was to meet the SCCA 5 liter (305 cid) Trans/Am regs.

SBC had a cross plane crank (and cross ram carbs - ob. thread).

Fun part was in the marketing: was rated at 290hp compared to the 350's 295hp (reality was more like 440hp). They wanted the squirrels to buy the 350.

Won a lot of trophies with mine (never could figure out why autocross trophies were so much smaller than drag racing).



(pic taken in late 60s - what we know as low profile tires today were called "cantilever tires" back then. Side pipes are a little hard to see)
 

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Premium Member 2005 SLK55 AMG
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625 Posts
Discussion Starter #18
The ":nerd:" appears - thank you for the inputs. Now beeing a bit more clever, or at least a bit more knowing. X-pipes and resonator box are now more understandable. Have to think this over:grin:, but the wife is under the impression that the car is loud enough:crying:. More to come, just don´t know how to hide it:wink:.
 

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Administrator 2009 SLK 55 AMG/Founding Member 2006
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The ":nerd:" appears - thank you for the inputs. Now beeing a bit more clever, or at least a bit more knowing. X-pipes and resonator box are now more understandable. Have to think this over:grin:, but the wife is under the impression that the car is loud enough:crying:. More to come, just don´t know how to hide it:wink:.
add whatever you want. Wife won't know the difference unless you tell her

When my car was gone a week for the Supercharger, I just said it was in for 'X' and they got the wrong part, so have to wait for 'X' to come in.

Here is 'X' :D

http://www.slkworld.com/performance-mods-r171/390442-my-kleemann-supercharger-adventure-pics-vids-all-over-thread.html
 
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