427r
 

I have one in my Backdraft. Went with it because I didn't want to have mess with the fuel injection. I am very comfortable working on Holleys. The engine has a serious lope to it at idle. Sounds like a muffled funny car. Does not like to be below 2k rpms. Very powerful after that all the way to over 6k and it gets there very fast.

I would simply start reading the topic titles. Do a search, but it would have to be very generic. There are TONS of topics in this forum on different engines and different engine builders.

My experience with my Roush 427IR was that if I were doing it again, and the engine were not already in the car, there are equal or even better alternatives for less money. Roush support is iffy at best (perhaps OK if you are really close but absolutely no support long distance, I had to ship my car to them and it got nothing until we figured out that the altitude compensation portion of their tune was "null" (ie, no compensation, incomplete.) I got nothing from them for that. They've since switched sources for the DFI (Digital Fuel Injection) controller and some reports are that it behaves better but still need some TLC for true low-to-high altitude operation since the self-learning system doesn't really know how to do it.

Bottom line, lots of alternatives, widen your search.

I do not own a Roush engine, and probably never will. After doing my research, that is not a company I want to deal with. Plus, you're paying a lot of money for the name.

If you want a complete driveline - from water pump to tail shaft - Call Mike Forte. He'll hook you up with everything you want or need, and for less than a Roush.

On the topic of this original post I'd almost say that Cobras are "over cooled". The huge radiator and oil radiator cause it in my opinion to run cooler than it should. Some have put a thermostat on the oil cooler and it helps some.

Couldn't agree more with Tony. I would replace the EFI system that came with that engine. Everyone has favorites, my favorite is Megasquirt's MS3Pro system. Excellent tunability, a self learning function to help get a base tune up and running and a tuner programming module GUI that is among the best I've ever worked with and it runs native (and identically) on either Mac or PC platforms.

An extra added attraction they have is an inexpensive (~$90) bluetooth transmitter / receiver that lets you program from your laptop wirelessly! Their data logging capability is on par with the best you're likely to find anywhere, which makes evaluating your tuning decisions much easier. An MS3Pro with wiring harness, tuning s/w, data logging s/w and a lifetime warranty is $1250.

If you want to buy an OEM wiring harness from an 03/04 Mach I or SVT Cobra you can get the MS3Pro Plug and Play version that uses the Ford OEM wiring harness and all the Ford sensors to eliminate the wiring harness fabrication headaches. The PnP version is priced at $1,350 and comes with a base tune to get the engine running.

You don't need to suffer the quirky, painful in town driving idiosyncrasies and bad manners of the early first and second generation engine management systems Roush offers, there are excellent alternatives.


Ed

Your choice of engine manufacture has a big name in the performance world, there is no doubt. There have been many threads on this site with tales of woe. Mostly oil burning. Mostly valve seals. They have been less than eager to make these problems right, based on these threads, therefore I have concluded they are not customer oriented. To be fair, I do not recall any problems with assembly. The problem's all seem to be they choose to use a 3rd party part that wasn't up to par.

The top notch small builders seem to only use quality parts and stand behind their engines a lot better. I think better engines can be purchased for the same or less money.

As for carbs verses EFI, first not all carbs nor all EFI are alike. In the older crowds eyes (who grew up with carbs and do not understand EFI) carbs are the pick. Simpler easier seem to be the opinions. The violent acceleration that a Cobra is capable of can slosh gas in the fuel bowls causing issues. Finding mechanics that have worked on carbs is going to be near impossible in the next 20 yrs. They are retiring and thinning out right now.

Some of the aftermarket EFI is geared toward drag racing. They run great at WOT. Drive-ability not so much. Throttle plate injectors are a step up over a carb, but not a lot better. IMO multi port injection is best.

EFI strategies are alpha-N, Speed Density, and Mass Air Flow. Alpha-N is very basic it mostly uses the throttle position and RPM to calculate everything. It is not very accurate, but it is fast. It also can always make a decent guess of what the engine needs under rapidly changing engine conditions. It is usually included in Speed Density and Mass Air Flow systems, as a sanity check and to handle rapid changes.

Speed Density uses a map sensor and throttle position to calculate and estimate what the mass flow of air into the engine is. On factory engines with mild cams this is pretty darn good. However you change anything and it needs re-tuned. Put a radical cam in it and it is very difficult to get a decent tune.

Mass Air Flow is the best technology, at least in theory. It actually measures the mass of the air flow into the engine directly with a heated wire. It doesn't matter what you change short of cid as long as you don't impact the accuracy of the mass meter. This is in my opinion the best strategy.

However when you get to very radical cams, you have all types of ugly things happening. Reversion flow into the intake, for one. The mass meter doesn't know which way air is flowing and can measure it twice (I believe there is a new meter now that addresses this). Exhaust gasses can carbon up the mass meter wires. Therefore there needs to be enough pipe to even out these pulses.

During the overlap (both valves open) un-burned air fuel can go into the exhaust. If it is not burned in the exhaust, it causes the O2 sensor to falsely read lean.

The most important improvement of EFI is a better control of timing. Timing is what makes the power. It also allows the CPU to better control the idle speed using timing. By setting the timing about half way to maximum torque at an idle, the CPU can pull timing out to slow the rpm or add more timing in to increase the rpm. At 600 rpm timing can respond in 10 milliseconds.

To sum this all up, a good EFI properly designed for the engine and properly tuned is much more accurate on fuel delivery, timing control, and idle control. You will never have to fight vapor lock, fuel bowls boiling over, and all the issues that come with a carb. EFI starts better, where carbs washes your cylinders down with gasoline wearing rings and contaminating oil. Hands down EFI beats a carb when it comes to drive-ability.

Is EFI worth the cost? Maybe not. Most of these cars do not have enough miles put on them to value a lot of this. However if you like the drive-ability improvements, it may be worth it to you.

Love that sentence " the violent acceleration that these vehicles are capable of" it really has to be experienced. There is a genuine rawness to it that keeps you on your toes. You better pay attention. I will agree about the fuel sloshing because I experience it not so much under acceleration but more during back and forth hard cornering. I am very comfortable around Holleys as I am almost 70 and grew up with them. They are not for everybody. How long has it been since cars were manufactured with carburetors. A long time. People just don't know how to work on them anymore and they are touchy.

I should add there is a lot of self tuning EFI advertising. In my opinion, it is all marketing and a few tid bits of truth sprinkled in.

At best these aftermarket self tuning EFI can be used to help you get a decent tune, although not necessary. A bunch of hype over something that always existed.

The factory CPUs all use correction tables of some type. They all self tune. They can usually correct the fuel up to +/-20% some more than that.

When you get all your fuel tables set correctly and then turn on the correction, you should see numbers very close to 0 in the correction tables. Letting it auto tune while you are trying to tune is like too many cooks in the kitchen.

To the best of my knowledge the only thing these auto tuning systems tune is the fuel. You still have to set the timing tables for your engine. The time is where all the power is at. Also you may need to run richer at WOT to keep some engines from going into detonation. I do not believe auto-tune is going to address any of this. All it is going to do is get the O2 sensor to read the commanded AFR.

So this all said do not let this self tuning hype sway you.

It really does need repeated. ;)

Odd, I can't get to page 2 of this thread.

Edit: Logged off and deleted all cookies then logged back in again, now works...

I think that anyone who looks at a self tuning feature as anything other than a tool to get a quick baseline start up tune to tune from is likely misleading themselves and potentially putting their engine at risk.

Generally speaking we get into trouble when we start using tools for things they were not designed to do. 'Self Tuning' is a misnomer and probably should have been called something else reflecting more closely what the tool actually provides, which of course is a base tune stepping off point to begin your actual tuning from.


Ed

Mike,I know you asked about temps and that was answered. A key in buying a ROUSH FI motor is to know the specific EFI system used. Roush switched many times. There was a period years back when they used a locked system and only roush could maintain. I suggest to check that our and be sure you have access to an FI mechanic famaliar with the specific system. JEff

I think you're referring to the initial period when they used the Accel DFI system. It wasn't really "closed". You could buy the PC USB dongle and software from Jegs and completely open it up (I did) and found that their tune was incomplete. It cost me several grand to get it finished. Most people never noticed because most never ran it into the segments where altitude compensation (which was "null") mattered.

Shortly after that they went to the FAST system and I don't know what they use today.

My bottom line is that I don't think the extra cost of a Roush over any number of equivalently built solutions is warranted. The primary reason is that their support isn't all that great to make up for the extra cost. In all fairness my car came with the Roush 427IR installed so I didn't have a say. It took over a year to understand what the issues were and get them resolved. I was minutes away from simply returning the car to Roush and having them swap the DFI for carbs when the tuner in Ft. Collins had me hook up the tuning hardware/software, read some logs, looked at the tune and explained what was going on. It was disappointing that Roush didn't even understand their own system well enough to fix it.

This was not the initial period. It was the 2nd or 3rd switch. There were upwards of 100 IR motors with the system. And I can confirm that is was locked. I will try to find reference to the brand.

Thanks

Jeff

Backdraft will start my build in May so this is really helpful guys as i have to chose an engine soon.

The more i research Roush the more I've started looking at smaller builders. I recently got in touch with Smeding performance who has a Cobra Special 427 600HP with a Borla 8-stack injection system. They have great reviews, low warranty claims and several write ups in hot rod mags and everytime i call or email they are right there. The numbers, especially torque look impressive but again I'm a newbie to the cobra world. Can someone who knows their stuff have a look at this engine and tell me what they think? Is this going to have a really rough idle and bucking at low rpm? Also if you've heard of Smeding Performance.
https://smedingperformance.com/colle...-8-stack-600hp

Thunderbird123 - feel free to PM me as I have first hand experience of Smeding and this exact same engine that went into my first BDR.

Sent PM

Hmmm - for some reason I didn’t receive it but I have just sent you a PM so let me know if you get it.

Andy

Dammit, now I want to know to!
:o

Basically, they didn’t build the engine right, it took a third party to find out what was wrong with it (intake manifold) as they couldn’t, they damaged the car when it was in the shop and their customer service was poor to non-existent. This was 2012 so to be fair to them things may have changed but there are too many others choices out there for me to give them a second chance.