American Speed 685 BHP engine

[ultimad]

Has anyone purchased the 685 bhp AS engine (I think it's 377 cu) and can give experience of reliability, usability on the road, etc. and any other general feedback. One thing I found out for example, is you have to have a special exhaust, which happens to cost over double the price of the 'standard' one. Any (useful) feedback would be greatfully received before I take (for me) a huge plunge. Assume I know sod all about engines and you won't be far off.

[stig]

ultimad said:

Has anyone purchased the 685 bhp AS engine (I think it's 377 cu) and can give experience of reliability, usability on the road, etc. and any other general feedback. One thing I found out for example, is you have to have a special exhaust, which happens to cost over double the price of the 'standard' one. Any (useful) feedback would be greatfully received before I take (for me) a huge plunge. Assume I know sod all about engines and you won't be far off.

Andy, first thing to consider is what you're looking for from the engine?

Power comes at a cost, that cost can be heat, lumpy idle, low mpg (170 mile tank range from my 630hp AS engine for example) and regular 'freshen-up' rebuilds. The .377 uses ally heads, so running one means you need to get it to temperature before going anywhere. They are far less tolerant than iron blocks in this respect and are likely to wear quicker. You'll really need to factor in a dry sump to the equation too, so set aside a couple more grand for that.

If setting records and using it at the strip is your thing, then it's a perfect engine for the job. If you're looking for more day-to-day use, a milder engine is a much better bet and I guarantee it will still frighten the life out of you If it makes you feel better, just tell inquisitive onlookers that it has 700bhp - they won't be able to tell the difference anyway, let alone recognise the car!!!!

Get Ted to take you for a ride in the demonstrator with the stock 350 chevy, then ask yourself whether you need to spend 20k more on bhp you'll rarely be able to use?

It's hugely tempting to look at the most shiny toys in the AS shop (I certainly did 1st time round with the GTR), but IMHO, as a more usable vehicle, a more stock engine is a better bet.

PS. I know that this sounds like a turnaround of opinion from me, but I can at least speak having had the experience of a monster Ultima I now happily subscribe to the Jack Rosen school of performance/usability thought


>> Edited by stig on Tuesday 20th September 16:35

[G Man]

ultimad said:

Has anyone purchased the 685 bhp AS engine (I think it's 377 cu) and can give experience of reliability, usability on the road, etc. and any other general feedback. One thing I found out for example, is you have to have a special exhaust, which happens to cost over double the price of the 'standard' one. Any (useful) feedback would be greatfully received before I take (for me) a huge plunge. Assume I know sod all about engines and you won't be far off.

You are talking about my car .... the exhausts are expensive because they are simply the best money can buy.They are equal length, longer primary pipes and repackable exhaust
The 377 is a bored out 350 using Chapman Racing head of 18 degree instead of 23 thus different exhaust port layout. Ti valves etc

This car is a very serious piece of kit which will not be happy posing in central London, it is incredibly quick and not for a novice.

It does a genuine 200mph ,

G Man

[GTRene]

G Man said:

You are talking about my car .... This car is a very serious piece of kit which will not be happy posing in central London, it is incredibly quick and not for a novice. It does a genuine 200mph , G Man

You lucky
So with that kit its not so relax cruising in town? hm... so mayby a LS6 with turbo's is a better allrounder? smoother and more resistend and reliable? even with the same power?
I still have to feel such power...can't wait because the fastest car I've ever driven is my Z3 M coupe S54 tuned, its "fast" but I got used to it and I want a car that is save but scares me when I put down the gaspedal full....
So thats why I want an Ultima GTR, and I love the looks ofcorse... a nice black one with more then 500hp will do...anny offers??
I saw the one on PH ofcorse but I don't have that amount of money sadly...I look every day on that site, but first have to sell my beauty...

René

[d3vine]

So how much of a performance difference between the 685bhp and the 700bhp 377ci? It costs few thousands more. Are there a big difference between these two for someone to pay more for it?

>> Edited by d3vine on Monday 19th September 23:14

[craig-ultima]

I have a 550 hp engine and the top end power (everything above 4000 rpm) right now is pretty much unusable on the street.

Right now the way I drive the car I can get a freeway ticket in about 5 seconds and lose my licence for six months in another 5 more seconds.

Once I get comfortable with the car and the transmission and all that, I should be able to get a ticket in about 3.5 seconds (70 mph) and lose my licence about 3 seconds later (100 mph). That's plenty fast enough for me! The power to weight ratio on the Ultima is insane. If you can't get a test ride in an Ultima, pretend to be interested in a Lotus Elise and get a test drive. The Ultima weighs maybe 150 pounds more, so not much. But the Elise only has 190 horsepower and not a lot of torque. Then think about tripling the power... nuts!!

Streetability is important. The aggressive cams make idling tricky. Mine will not idle until it has warmed up (that may be something else, but my manifold has no heat, and I've heard this causes problems until the whole engine is warm). My engine is generally okay, but it has some odd characteristics in that it can sputter a bit if I put too much gas on below about 1800 rpm. The sweet spot for regular driving seems to be 2000 to 3000 rpm. Power kicks in above 4000 (supposedly - I haven't gotten there yet!) A more stock engine would probably behave better, and I can only imagine that a more aggressive engine would get even more sensitive.

From my limited understanding of engine building - it is all about compromises. Where the power occurs in the RPM band, fuel economy, emissions, reliability, stability, streetability. Spending more money on better parts is all about pushing power out and all those other areas get compromised.

[ultimacz]

Come on guys, why are you all so scared of huge power? I had the original AS 383cui 450HP engine and it was by far not powerful enough to frighten me. The Ultima can handle much more power. The engine had quite some good torque but did not rev well above 5500 and the end was already at 6200, and I felt that high revving "hurts" the engine. My current custom build 383 engine has true 550 HP or above, the cam was chosen so that it revs up to 7400 and has the power peak at around 7000, that´s much more to my taste. Still a lot of torque at the bottom but it goes like hell at the top and revs up so fast that I frequently get into the rev limiter. And there is still the feeling that the car could handle easily more power. I actually use the power when overtaking savely on public roads, would not like to miss one single horse. And I am still not frightened, it is just a great feeling to "sit on a rocket".

And to heat up the discussion even more: concerning fuel consumption, cold starting, heat generation, oil burning, idle behaviour, etc., it does not really matter which type of SBC you have (whether 350HP or 685HP), they are all a desaster compared to modern production engines with electronic motor management. SBC is simply what it is: cheap power. So either you are looking for a really useable engine (as a daily driver) then look somewhere else, or if you go for cheap power with all advantages and disadvantages, then why shouldn´t you go for the ultimate thing and enjoy it?

P.S.: I have driven the car now for nearly 10.000 miles, never got into really unsafe situations and very frequently used the full power. Everything just my opinion of course, don´t want to talk anybody into something he/she can´t handle...

[mclark]

Stig,

You mention "low mpg (170 mile tank range from my 630hp AS engine for example)".

Was this the total range for both tanks (not each tank)?

Michael

[G Man]

ultima factory said:

The 685bhp engine and all of the OE engines for the Ultima offered by American Speed are great for road use.

I agree it is a great engine

ultima factory said:

Gman I beg to differ regarding using your car around central London it will be fine in this environment. In fact I went to central London with a mate who knows his way around last month in our GTR640 demo and it was fantastic fun as yours was when I drove it in central Nottingham prior to the record runs. Your GTR685 and our GTR640 idle beautifully at 700rpm once warm and won't overheat in traffic even if left idling all day long. Supercharged engines aside sensible driving will give over 20 miles per gallon.

Yes my car does idle perfectly at 700rpm I personnally don't pose in cities, I am not worried about overheating but more the hassle of gear changing

ultima factory said:

The factory wouldn't recommend these fabulous engines as options for the Ultima if they weren't suitable for road use in all conditions. 350bhp is enough power for the road but there is a certain pleasure knowing that an Ultima with over 600bhp can out accelerate such greats as the legendary Mclaren F1.

Would you stop selling these engines I know they are good so do you, but we don't have to tell anyone do we !! I think a Ford Sierra 2 litre is much better suited and is G Mans recommended engine

G man

[GTRene]

[quote=ultimacz]just a great feeling to "sit on a rocket".

And to heat up the discussion even more: concerning fuel consumption, cold starting, heat generation, oil burning, idle behaviour, etc., it does not really matter which type of SBC you have (whether 350HP or 685HP), they are all a desaster compared to modern production engines with electronic motor management. SBC is simply what it is: cheap power. So either you are looking for a really useable engine (as a daily driver) then look somewhere else, or if you go for cheap power with all advantages and disadvantages, then why shouldn´t you go for the ultimate thing and enjoy it?

But does a LS1-6 modern engine also have those "problems"? or are these just fine and good to drive without the "problems" above so you can have the best out of 2 worlds....?
Because I hope to buy one in the near future, and that would be my only car then!, so it has to be good...so I hope the LS1-6 engine's don't have the things I don't like as the story above.

René

[andygtt]

I agree with Ultimacz, my 500+bhp canam was easy to drive and hardly a monster (unless I asked it to be).
The car communicates loads more to the driver than any production car and so you always know what it going on.

[mhussa]

I have some questions for the experienced ultima builders/drivers.

What is a good "middle way"? in terms of engine choice with respect to reliability (mostly), maintenance, econonmy.

I'd read somewhere that overheating problems could be addressed by richening the mixture, but doesn't more unburnt fuel get thrown out of the exhaust? An image of road-runner burning a trail past coyote comes to mind.

A couple of months ago I drove behind a sierra cosworth which was spitting out big flames and kept well back (i didn't want my eyebrows singed). Not very nice.

I think engine choice could also affect resaleability in the long term anyone have any experience with this?

Thanks in advance.

[ultimad]

Crikey now I'm confused (not hard). This won't be my regular driver so I'm not too worried about little quirks such as a bit of oil consumption, low mpg, a certain amount of erratic idling whilst cold etc. What I really don't want is the hassle of having to have the engine rebuilt (at least not for a very long time) or requiring regular specialist maintenance. Most of its use will be on the road (probably no more than 5-10% on track). The factory nailed my sentiments entirely about the extra power of such an engine. My feeling is that if you go through this kind of experience building your dream supercar why not go the whole hog and put a great engine in it. Can I achieve all this with the 685 or am I being naieve ?

[G Man]

Ok get in your car drive to West Oxfordshire and I'll show you 685 bhp .... about 35 minutes from you or 20 Ultima minutes

G Man

[stig]

mclark said:

Stig, You mention "low mpg (170 mile tank range from my 630hp AS engine for example)". Was this the total range for both tanks (not each tank)? Michael

That was the range of both tanks combined (what with it being the Supercharged 'aside').

>> Edited by stig on Tuesday 20th September 16:04

[stig]

ultima factory said:

The factory wouldn't recommend these fabulous engines as options for the Ultima if they weren't suitable for road use in all conditions. 350bhp is enough power for the road but there is a certain pleasure knowing that an Ultima with over 600bhp can out accelerate such greats as the legendary Mclaren F1.

So there you go. 350 is enough for the road, 600 will help when taking on a Macca F1 at the lights

I loved my GTR (or I suppose it should be GTR630S given the nomlecature that seems to be emerging) and a mega-performance car is indeed, a fantastic ownership experience. Just be realistic about what you're after from the car.

Either way, the AS engine range will not disappoint. You just need to decide how much you want to spend and what sort of performance you expect in return.

>> Edited by stig on Tuesday 20th September 16:31

[layada]

IMO general streetability is assocaited to how wild the cam is and higher up the revs, the forced induction method used (should it be employed)

So suggest for the road, choose 'fast road' cam and for forced induction use a supercharger (more linear output) rather than turbo chargers. These two aside, go for all the power you can afford!!

[mhussa]

I can see the following pattern emerging:

350 hp - comfy
450 hp - naughty but nice
550 hp - razors edge
650 hp + twilight zone

At the moment the 450 zone seems to be a good compromise budgetwise for me. The higher bhp flamethrower version could be useful the next time the neighbour walks their dog, hmmmm interesting possibilities.

Looking at this from a different perspective there is also a question of those damn numbers, for example the ultima640 gets lots of attention because of its achievements but even with less power the car is formidable. From the fastest PC to the fastest Car those numbers appear and make the majority of men take interest. cest la vie.

thanks

[bluesatin]

I run a 525 enforcer with significant modifications which include a lot of port grinding, hp carb and a new very wild cam. American spped mentioned that the cam should give an extra 25bhp plus some extra from the carb to give say 560 american bhp. The cam give zero vacume at idle but the car is happy at 900rpm and does not overheat. I maxed the car 15 times last weekend and drove approz 150 miles on the road. Road driving returns close to 20mpg so all in not bad.

[USCANAM]

stig said:

[ PS. I know that this sounds like a turnaround of opinion from me, but I can at least speak having had the experience of a monster Ultima I now happily subscribe to the Jack Rosen school of performance/usability thought >> Edited by stig on Tuesday 20th September 16:35

Chris
I guess you noticed that the CanAm did not have enough performance for me, so I just recently purchased a 1955 MG TF. Please notice that this has the 1500cc engine, not the piddley 1250 cc engine of the earlier TF's.
Actually, it's a lot of fun, and I have a lot of time to fix the oil and fuel leaks since all I have to do with the CanAm is gas and wax it. Even with only 357 RWHP, I still do 60 in 3.3, and 100 in 7 seconds. Over 10,000 miles on the car, and have only had the rocker covers off to adjust the valve clearance. Big mistake, was the solid lifters, and so was the Edelbrock 3500 EFI, which as I mentioned in earlier posts. This is in the process of being modified to a MAF system as soon as all the parts arrive.
Sure the car can handle double the power I have, but as you mentioned, why sacrifice the reliabilty unless this is to be only a track car.
When I open the bonnet at a show, the power package is so impressive to the eye, that any horsepower that I quote to the question of power output is accepted without question. That more than fulfills the phallic demands!!!
I am hoping that with the modified EFI, the fuel mileage will improve above the 15 mpg (American), and slow traffic driving will be smoother.
Oh, and with the over 10,000 miles on the Pirelli's, they still look like new.
Another thought...When you KNOW that you're driving one of the fastest cars in the State, you don't really have to prove it!!
I see your build is progressing well. Love the carbon fiber. Lot better than all the polishing!!
Regards
Jack