Talkin Torque

[QC]

Re: Talkin Torque

Good comparative data, from the same hulls, is very difficult to find. I will be blown away if anybody has anything substantial or valuable to provide.

 

[Don S]

Re: Talkin Torque

Good comparative data, from the same hulls, is very difficult to find. I will be blown away if anybody has anything substantial or valuable to provide.

I agree.
The fact that neither OMC nor Volvo (the only ones that used Ford and Chevy engines with outdrives in 95) publish torque specs on their engines means you aren't going to find any specs on either.

Even if you did have torque specs, you would have to have identical boats, identical drives, identical weather and sea conditions along with a lot of special testing equipment to find out anything worth while. And that isn't going to happen either.

 

[Tail_Gunner]

Re: Talkin Torque

The 4.3 gm motor has been a guniea pig for Gm for years, There are more combination of heads for that engine its almost unbelieve. Tbi heads..votrec heads (3-4 different types) non vortec heads. It has gone thourgh a huge evoltion...Its just a matter of evolution. Do some reading here's a link But in end i believe it all leads to head design and cam profiles and gm spent big money on it. On the ford your pretty much limited to the gt40 heads.

GM: WIKI - 4.3

Ford: http://en.wikipedia.org/wiki/Ford_Windsor_engine#302

 

[Silvertip]

Re: Talkin Torque

Did you not go to the link I referenced and look at the 305 torque figures. These are marine engines -- not auto engines. And I did indicate I did not have charts for the Ford 302. So show us a marine 302 torque curve. They are out there somewhere. I'd even settle on one for a car. Never mind, I did the search for you. Let me make this perfectly clear -- this is a 400 HP "built" 302 so hardly a fair comparison to either an auto or marine based 305 GM. Torque is rather lofty at something over 350 lbft but HP is does not begin to build meaningfully until well up in the RPM band. Not exactly what you want for anything other than a boat with an ON-OFF switch for a throttle. Bore and stroke combinations are used to meet certain performance requirements as GM has so aptly done with the small block. There have been some combinations that are remarkably close such as the 302 Z28, 305, and 307. All of those engines have different bore/stroke combinations and as is usual, regardless what the displacement numbers are, in stock form, any engine in those displacements will have maximum torque that generally falls very close to its displacement.

 

[Tuna Van]

Re: Talkin Torque

Thanks for all the replies. It looks like everyone is going to have to bring me all their boats, and I will strap my G Tech to them and collect all the data. Then I will compile a database to reference. How does tomorrow work for everyone?

 

[QC]

Re: Talkin Torque

I'm busy how about Wednesday?

Silvertip,

I am confused by the curve you posted and the assertion that it would suck as a marine engine. I went to the GM link you provided, I had missed that. Great info there!!! Here is the published 305 "curve" by GM from there:

Looks very similar (straight) to what you posted as do all of the curves there.

Back to your link for a minute. Like WOW!! Has brought me more questions than answers . . . let me put it this way. None of you should go to that link, and definitely do not go the Marine engine section, and whatever you do, do NOT look at the 6.2 SC specs . . . Holy Flyin' Flip, WTF!!!! You have been warned

 

[Silvertip]

Re: Talkin Torque

QC: The Ford 302 (400 HP) obviously has a cam that would suck the lake dry due to reversion in the exhaust before you got away from the dock. My comment regarding its use as a boat engine was applicable to a daily driver/cruiser rather than simply a go fast boat -- hence the On-OFF switch remark instead of a throttle.

Not sure I follow your reasoning for going or not going to the web site I posted. (Unless you are salivating over the SC stuff).

 

[QC]

Re: Talkin Torque

Salivating . . . Also, small block vs. big block insanity As I have said, I am an engine guy, I love power density improvements, especially from a large OEM. 100 bhp per liter is not a big deal anymore. My son's GTI has that and it also is nearing 100K miles. You can have your cake and eat it too these days as far as power to weight and power to displacement discussions are concerned.

 

[45Auto]

Re: Talkin Torque

Great link on those GM marine engines, Silvertip! Been wishing we had that kind of info for a long time!

Here's a couple of dyno pulls on a stock 96 Mustang GT, the last year of the 302 (5.0L) before they went to the "modular" 4.6L I believe. I can see why Ford was run out of the marine business - fairly peaky torque curve with a max of 275 ft-lb, and it struggles to make 200 HP.

 

[Tuna Van]

Re: Talkin Torque

Thanks 45Auto. Looking at this curve (yeah I know auto not marine) it looks like the 5.0 makes good low end power but runs out of steam pretty early. The way my boat is propped now I get out of the hole quickly and top out at about 46mph at 4600 RPM at WOT which is right at redline. I wonder if running a different prop to lower that to about 4200 would help my top end without a noticeable difference in hole shot. I guess I need to find a prop shop and find out.

 

[Silvertip]

Re: Talkin Torque

Those charts have been around for quite some time. Thought everybody knew. If it's a small, light weight power package one is interested in, the 3.8L Buick Grand National engine with a few tweaks would make an interesting study. Yes, getting rid of the turbo heat would be an issue but those engines were light and made great power. Even the venerable 283 Fuelie was available with 315 HP back in 1959 (may be off a year). Most folks think 283/283 was the max that engine ever produced in stock form. Small engines can make big HP but as displacement goes up, rotating mass and pumping loses begin to take their toll so one begins to see diminishing returns. In 1956 it was a big deal for a bone stock Chevy Bel Air 4 door 265 V8 to hit 60 mph in less than 10 seconds as the advertising indicated. Heck my Impala with a 3.5L V6 blows the doors off that and gets 50% better fuel economy in the process. But then I suspect 0-100 MPH might produce a different result. Yes -- progress has been made.

 

[QC]

Re: Talkin Torque

Those charts have been around for quite some time.

I am still confused by what they show there as I see no indication that Merc or Volvo buy those "complete" marine engines. It does look like PCM and Crusader are using the 6.0 with the latest ignition and aluminum heads. We'll see. What is also confusing is that I don't believe GM has done any development with a Catalyst, so if you are a packager of complete marine engines you MUST have your own engine development cells and group. I am sure they use places like Southewest Research, but I don't see how GM has added enough value to result in widespread sales of the high performance stuff. Seems like there is no way to simply take those engines, add drives and transmissions and sell them. So IF you have to do development yourself in any volume, why pay GM for completes that are not ready for the market? It appears that's what the big guys have concluded.

 

[45Auto]

Re: Talkin Torque

Hey Tuna, just found out that '96 was the FIRST year of the 4.6 modular motor and the '96 and '97's have a reputation for being pretty anemic. So the chart in my post above is NOT for a 5.0 but for a 4.6. Sorry about that. Dyno chart below is for a 5.0:

As you said, it's automotive and not marine, but will hopefully get you in the ballpark. Looks pretty close to the 305 Chevy, torque curve appears to be slightly peakier and a little lower.

 

[Tail_Gunner]

Re: Talkin Torque

I am still confused by what they show there as I see no indication that Merc or Volvo buy those "complete" marine engines. It does look like PCM and Crusader are using the 6.0 with the latest ignition and aluminum heads. We'll see. What is also confusing is that I don't believe GM has done any development with a Catalyst, so if you are a packager of complete marine engines you MUST have your own engine development cells and group. I am sure they use places like Southwest Research, but I don't see how GM has added enough value to result in widespread sales of the high performance stuff. Seems like there is no way to simply take those engines, add drives and transmissions and sell them. So IF you have to do development yourself in any volume, why pay GM for completes that are not ready for the market? It appears that's what the big guys have concluded.

I have been doing quite a bit of research lately on the 4.3 which is closely tied to the 5.7.Gm has done volumes of updates on head design and applied the results to both the 5.7 and 4.3 And being in the auto ind most if not all of the hp advancer's have come from air induction system's and ecm programming.

Ford long ago abandoned push rod motor's in favor of OHC motors. The duratech line which is the 2.0-3.0 soon to called ECO boost motors..The Triton motor's in the 4.6-5.4 and 6.0. Using synthecis to build intakes and finally going to 3valve designs and today they have a little 281 cu that does 320 hp that is as solid as rock...(Mustang) OHC in a boat..not

Gm on the other hand seems to keep with there push rod motor's, and doing a lot of development with head and cam tech. Here is a older link showing just how much they have done.

http://www.thirdgen.org/techboard/tbi/336750-tbi-tpi-heads-headflow.html

Middle of the page

EDIT: This post (WOW!!! GMPP Aluminum Vette Heads) describes just how good the factory L98 head castings are now, after 10+ years of tweaking to the casting (back cut valves, smooth radii etc). So the newest 113 casting have nearly no room for porting... although the owner did use sanding rolls before he got them flowed

You have to read it all but Gm has been going a different path increasing effiecny and selling on hell of a lot of low cost boat motor's along the way. Note the tinkers do not any longer port the newest heads.

I seriously doubt other than mapping ecm's Volvo or Merc do little else than buy prepacked engine's speced out to there liking. I do expect some or would think changes.... in just how they setup there ecm's, from what i have read so far they run the motors in a overly rich condition for safety reason but with the new epa regs coming down that should change.

Take it a bit futher, you work in deisel tech. I am sure you know of Ford's law suits with Navistar on the 6.0 and failure rate's...Navistar sold Ford the tech..prepackaged,

 

[Tail_Gunner]

Re: Talkin Torque

Thanks 45Auto. Looking at this curve (yeah I know auto not marine) it looks like the 5.0 makes good low end power but runs out of steam pretty early. The way my boat is propped now I get out of the hole quickly and top out at about 46mph at 4600 RPM at WOT which is right at redline. I wonder if running a different prop to lower that to about 4200 would help my top end without a noticeable difference in hole shot. I guess I need to find a prop shop and find out.

That prop is doing quite well, going up two pitches will only make your hole shot suffer and a high chance you will lose 2-4 mph. One opition that would make sense is going to a merc Enertia spendy but you might be able to up a pitch keeping your hole shot and a better top end along with increased midrange.

 

[QC]

Re: Talkin Torque

Take it a bit futher, you work in deisel tech. I am sure you know of Ford's law suits with Navistar on the 6.0 and failure rate's...Navistar sold Ford the tech..prepackaged,

Yeah, I do and this kind of goes to my point. We are talking with a US Truck OEM right now about taking an Asian diesel and certifying to US emission regs for them. The point is, without us, they would have to open a whole new shop to develop and certify, or they have to contract that work out to someone else (like us). We bring a couple of other benefits to the deal, but IF GM does not emission certify, then who can they sell "complete" engines to? Only those that are willing to pay for a "complete" and then spend a lot of money on it. Whereas, Merc and Volvo buy an "incomplete" engine and do a significant part of work themselves, even assembly, but until this year they had the volume to support that level of work . . . So I am confused about who those super duper 6.0s and 6.2s are targeted for. Certainly not set up for any volume with the business models they seem to be forcing . . .

 

[Silvertip]

Re: Talkin Torque

If you look at the fine print in all of those tech sheets GM does indicate actual output figures depends on ECM programming. That would tell me that the boat manufacturers will be able to specify what they want tuning-wise. It does not however indicate who will handle addition of the converter and emissions certification. Perhaps GM will do that but because this entire emissions deal is not fully thought out across the country, they won't do anything until those requirements are fully defined. But then perhaps GM has already tested those engines and with the sophisticated ECM's they become self-tuning for lack of a better term regardless who adds the cats or where the cats came from.

 

[QC]

Re: Talkin Torque

Yeah, and my experience is that the engine doesn't care about the cats with the exception of back pressure, so that is kind of automatic. O2 in the exhaust is there as a "loop closer" anyway . . .