Roush 427 SR verses R

[Gus M]

For a weekend driver and for road cruises, which engine is preferred?

[Lou1119]

Originally Posted by Gus M

For a weekend driver and for road cruises, which engine is preferred?

The SR is much more street friendly and suited for your needs.

[SwiftDB4]

Totally agree.

[ha_pe_1968]

Hi!
I have the 427R - it makes a lot of fun on spirited montain drives :-)
After some ignition modifactions and other carburetor street manners are ok - but it's not a cruiser. As already stated the SR is more street friendly. Over 3.500 rpm you will notice the power difference.

Peter

[Gus M]

Thanks for your invaluable input!

It's important to me when driving around town when coming off of a stop light, that the car not buck or if making a turn from a stop position, not stalling waiting for the torque curve to kick in. Obviously the SR and the R were designed for specific use. For my needs and use, between the two, the SR seems to fit the bill. Thanks again!

[FredG]

I have the R. It reminds me of the full race engines of the 60's. Very lumpy idle, very low end torque, explosive power over 3k rpms. I love it.

Fred

[Kawman]

Gus,

The difference between the SRX and the SR is, the SRX uses the aluminum heads as cast (480hp). For $600 more, the heads are ported and polished, getting another 30hp from improved airflow and that is the SR (510hp).

The R engine uses a bigger cam and you go from a dual plane intake to a single plane intake. Now you get 550hp, but at a bit of a cost in terms of a more pleasant street driver.

What do you need the extra 40hp for when you already have 510hp in a 2,400lb car? Don't get me wrong, I'll happily sell you whichever you want, but my advise would be to go for the SR.

I've got one in stock if you need it.

[Gus M]

Originally Posted by FredG

I have the R. It reminds me of the full race engines of the 60's. Very lumpy idle, very low end torque, explosive power over 3k rpms. I love it.

Fred

I really love the lumpy sound of the 60's being an old Mopar 440 and 426 guy.

I would like to try the R but my concern with the R is off the line from a stop light...will it bog? From a stop making a turn, will it stall until the torque curve kicks in (won't be at the 3k rmp) ? And can I take it on a 200 + mile cruise without issues?

Any videos on the R off the the line in street driving?

[Gus M]

Originally Posted by FredG

I have the R. It reminds me of the full race engines of the 60's. Very lumpy idle, very low end torque, explosive power over 3k rpms. I love it.

Fred

I really love the lumpy sound of the 60's being an old Mopar 440 and 426 guy.

I would like to try the R but my concern with the R is off the line from a stop light...will it bog or do the jerky bounce? From a stop making a turn, will it stall until the torque curve kicks in? And can I take it on a 200 + mile cruise without issues?

Any videos on the R off the the line in street driving?

[rodneym]

Everyone says get the SR.
And the buyer always gets the R - can't help themselves.
Seriously, get the SR.

[Gus M]

funny you say that...I find myself thinking the same!

[twobjshelbys]

I had the fuel injected version - 427-IR - which has the R type cam. I liked it once I got the fuel injection straightened out.

[jhv48]

Originally Posted by Gus M

funny you say that...I find myself thinking the same!

You’ll regret getting the R if street driving and cruising is your goal. I got the SR and had thousands of miles of enjoyable driving. However, it comes with a vacuum secondary Holley street avenger carb that works fine in a two ton automobile. But when it comes to our 2500 pound rocket sleds, you’ll quickly ditch it for a mechanical secondary four barrel Holley. Then the fun begins.

[Gus M]

"quickly ditch it for a mechanical secondary four barrel Holley"

Like the Holley 777?

[Gus M]

deleted

[ha_pe_1968]

Hi Gus!
Easy decision - do what most do...order the 427R and try to make it a lil bit more street friendly :-)
The lumy idle sound and the pull over 3.500rpm will help to forget that you do not have the engine which you wanted and which make sense.
Order with a dual plane intake, go for a smaller carburetor with mechanical secondaries, check the ignition curve and you will be more or less happy :-)

Peter

[FredG]

I keep the idle a tad higher and just need to use a few more rpms to get it going. After that, it's fine and you can drive it anywhere. If I wanted something that was more streetable, I would have bought an automatic Vette or put in one of those Iconic things. You should probably try to drive one.

Fred

Originally Posted by Gus M

I really love the lumpy sound of the 60's being an old Mopar 440 and 426 guy.

I would like to try the R but my concern with the R is off the line from a stop light...will it bog or do the jerky bounce? From a stop making a turn, will it stall until the torque curve kicks in? And can I take it on a 200 + mile cruise without issues?

Any videos on the R off the the line in street driving?

[MKS427]

SR has dual plane manifold (street/torque oriented) vs single plane on R (more WOT/high HP oriented). The car is so light, you can really go either way.
I have the Craft equivalent of the R with a Performer RPM Air Gap. I ended up switching to an EFI ($1200 system) to tune around the low vacuum, which the carb didn't like below 1800 RPM. If you choose to go this way, let the engine builder know and ensure they use an EFI friendly camshaft.

[hauss]

If you want a cruiser get a TR6. You will not stall with a 550 hp car. You are in a Cobra! and it should act and sound like one. Get the R .Just make sure you upgrade your cooling system. One more thing either way you go I am sure you will be happy good luck and most important . HAVE FUN!

[FredG]

I took this last summer. It brings a smile to my face standing next to it when idling.


https://www.youtube.com/watch?v=BGr5pwibxxw


Fred