What are the internal differences between the S4 engine and the RS4 engine?

FixedWing · 10-05-2005, 02:23 PM

I have been thinking that I would source an RS4 engine in Europe and swap it into my car. Now I'm wondering if this really makes sense? I have been thinking that it makes more sense to start with an RS4 engine and work on increasing the power of that rather than to start with a basic S4 engine. But are there any real differences that justify this?

There doesn't seem a lot of information in the archives on the real differences between these two engines.

Stephen

Todeshandler · 10-05-2005, 02:27 PM

would be any different. The best option would be to source a whole RS4 drivtrain, tranny, ecu, long block, and all intake & fuel system/plumbing.

nyet · 10-05-2005, 02:31 PM

like brian said, if you are interested in other parts (cams, tranny, fueling, etc) it only makes sense if you are getting them all part of a whole pkg deal.

FixedWing · 10-05-2005, 02:37 PM

"[T]he cylinder head has been redesigned and produced using a specially developed casting technique. The admission and exhaust ports have been modified in line with the engine's higher performance, and the cross-section of the air ducts at both the intake and thrust side enlarged."

So how much difference does the head work make?

Stephen

The RS4 by quattro GmbH

blslhi · 10-05-2005, 02:38 PM

I think you can have just as reliable, durability wise, with s4 engine as you would with a RS4.

Small Town Terrorist · 10-05-2005, 02:39 PM

Small Town Terrorist · 10-05-2005, 02:40 PM

Just-Emre · 10-05-2005, 02:40 PM

Johnny Bravo · 10-05-2005, 02:42 PM

Pistons.
Mahle brand ( assumed since its aslo stock for us )
Larger Gideon Pin ( wrist pin ) and more prononced
dish. ( not sure if it accounts for any change in CR, since the Headgasket is pretty thick )

Rods.
Differnt to accept larger wrist pin
Rod bolts are M9 instead of M8.5

Crank.
Different Crank Same dimensions different materical according to the SSP from Audi.

Heads.
Similar to the 2.4L euro heads.

Main Caps.
Cast steel. I dont know what the s4 has.

Cams.

Intake Manifold.

I would build an S4 block.
Stock Rs4 Pistons,
anything but x-beam rods.
2.8 heads, or ported 2.7heads.
talk to Istook for crank.
maybe block fill 25%

done!

FixedWing · 10-05-2005, 02:44 PM

As a matter of economics, I think it makes sense to get the entire engine/transmission as a single unit.

There is a difference to the transmission which makes it worth having (closer ratio 3rd and 4th gear) and a difference to the central differential that makes that desirable too.

The compression ratio is slightly lower on the RS4 which is also desirable.

But I guess most of the internal differences are in the heads. Anyone know how much bigger the valves are -- if they are even bigger?

I agree that it makes sense to use all of the fuelling, etc. from the RS4. Again, it makes the most economic sense. Getting all of this with the engine is what justifies the price as this is what is expensive to build an engine here.

Not sure about which ECU to use though. If I use the RS4 ECU, then I need the instrument cluster and to re-wire for that. Why not use a modified ECU from the USA? Surely the set-up is almost identical? Then home-brew.

Stephen

10-05-2005, 02:23 PM	#1
FixedWing Senior Member Account #: 66531 Join Date: Dec 2003 Posts: 7,155	What are the internal differences between the S4 engine and the RS4 engine? I have been thinking that I would source an RS4 engine in Europe and swap it into my car. Now I'm wondering if this really makes sense? I have been thinking that it makes more sense to start with an RS4 engine and work on increasing the power of that rather than to start with a basic S4 engine. But are there any real differences that justify this? There doesn't seem a lot of information in the archives on the real differences between these two engines. Stephen __________________ ================================================== ======================

10-05-2005, 02:27 PM	#2
Todeshandler Member Account #: 71856 Join Date: Mar 2004 Posts: 5,699	If you can source an inexpensive RS4 long block it would be worth it. Not sure if the short blocks would be any different. The best option would be to source a whole RS4 drivtrain, tranny, ecu, long block, and all intake & fuel system/plumbing. __________________

10-05-2005, 02:31 PM	#3
nyet Member Account #: 13093 Join Date: Dec 2000 Posts: 33,114	afaik not much different in the bottom end like brian said, if you are interested in other parts (cams, tranny, fueling, etc) it only makes sense if you are getting them all part of a whole pkg deal. __________________ ------------------------------------- "It's easier to practice medicine without a license in this country than it is to get info on tuning Motronic." -JasonS9 ECUxPlot - my java based ECUx/VAGCOM/VCDS plotter My hacked version of Flyboy's ECUx template. S4Wiki - CONTRIBUTE TODAY! Web based FATS calculator for ECUx and VAGCOM logfiles Sync your iPod under Linux! Definitive S4 DIY Thread of Doom AWOT Brain Trust #101 AWOT Axis of Evil Member #6 Member, Aw0t Fish Taco Dinner Club I say to you that the VCR is to the American film producer and the American public as the Boston strangler is to the woman home alone." - Jack Valenti, President and CEO of the MPAA this site is NOT for information sharing it's strictly for multiple monologues that result in none of the participants changing their point of view - frank

10-05-2005, 02:37 PM	#4
FixedWing Senior Member Account #: 66531 Join Date: Dec 2003 Posts: 7,155	From the original Audi AG press release... "[T]he cylinder head has been redesigned and produced using a specially developed casting technique. The admission and exhaust ports have been modified in line with the engine's higher performance, and the cross-section of the air ducts at both the intake and thrust side enlarged." So how much difference does the head work make? Stephen The RS4 by quattro GmbH __________________ ================================================== ======================

10-05-2005, 02:38 PM	#5
blslhi Junior Member Account #: 61095 Join Date: Aug 2003 Posts: 942	Law of diminishing returns. That is what I think going out and getting a rs4 motor will be. I think you can have just as reliable, durability wise, with s4 engine as you would with a RS4.

10-05-2005, 02:39 PM	#6
Small Town Terrorist AudiWorld Super User Account #: 11272 Join Date: Oct 2000 Posts: 2,417	heads, Oil Circuit, Con rods, Conrod bolts, etc I've got more info somewhere me computer. __________________

10-05-2005, 02:40 PM	#7
Small Town Terrorist AudiWorld Super User Account #: 11272 Join Date: Oct 2000 Posts: 2,417	I say purchase a used s4 engine and build it. __________________

10-05-2005, 02:40 PM	#8
Just-Emre Member Account #: 94085 Join Date: Jul 2005 Posts: 3,736	Isn't the RS4 a 2.8, while the S4 is of course 2.7?

10-05-2005, 02:42 PM	#9
Johnny Bravo AudiWorld Super User Account #: 6784 Join Date: Jun 2000 Posts: 5,384	.... Pistons. Mahle brand ( assumed since its aslo stock for us ) Larger Gideon Pin ( wrist pin ) and more prononced dish. ( not sure if it accounts for any change in CR, since the Headgasket is pretty thick ) Rods. Differnt to accept larger wrist pin Rod bolts are M9 instead of M8.5 Crank. Different Crank Same dimensions different materical according to the SSP from Audi. Heads. Similar to the 2.4L euro heads. Main Caps. Cast steel. I dont know what the s4 has. Cams. Intake Manifold. I would build an S4 block. Stock Rs4 Pistons, anything but x-beam rods. 2.8 heads, or ported 2.7heads. talk to Istook for crank. maybe block fill 25% done! __________________ Aim: Johnaudi mail: Johnaudi / Aol.Com

10-05-2005, 02:44 PM	#10
FixedWing Senior Member Account #: 66531 Join Date: Dec 2003 Posts: 7,155	That's what I would do. As a matter of economics, I think it makes sense to get the entire engine/transmission as a single unit. There is a difference to the transmission which makes it worth having (closer ratio 3rd and 4th gear) and a difference to the central differential that makes that desirable too. The compression ratio is slightly lower on the RS4 which is also desirable. But I guess most of the internal differences are in the heads. Anyone know how much bigger the valves are -- if they are even bigger? I agree that it makes sense to use all of the fuelling, etc. from the RS4. Again, it makes the most economic sense. Getting all of this with the engine is what justifies the price as this is what is expensive to build an engine here. Not sure about which ECU to use though. If I use the RS4 ECU, then I need the instrument cluster and to re-wire for that. Why not use a modified ECU from the USA? Surely the set-up is almost identical? Then home-brew. Stephen __________________ ================================================== ======================

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode


Discussion Forums:	Advanced Search