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Maybe I missed it in the article, but unless the engine is going in a big Olds 98 or other heavy car handicapped with 3.08 gears, I’d hope for much better than mid 12s!
My question is: What good is a engine that peaks @ 5000 RPM and starts dropping off like a rock at 5250 with under 450 TQ @ peak HP. I will never understand why people put a 4.500 stroke in those engines. Looks like the shop does decent work though. And BTW who knows what those dyno numbers mean with no test data, numbers could be conservative, although I don't think the power peaks are mis represented.
My question is: What good is a engine that peaks @ 5000 RPM and starts dropping off like a rock at 5250 with under 450 TQ @ peak HP. I will never understand why people put a 4.500 stroke in those engines. Looks like the shop does decent work though. And BTW who knows what those dyno numbers mean with no test data, numbers could be conservative, although I don't think the power peaks are mis represented.
Can you please elaborate? From the graph it looks like TQ is over 500 at peak HP which they stated was 488 HP at 5000 RPM. The graph does appear to show HP peaking closer to 5200, but even there, the TQ looks to be well above 450. And since HP = TQ * RPM / 5252, at this crossover point, it still looks like they’re about 480.
What I don’t understand is why the HP starts dropping off around 5400 RPM. Are you seeing anything in the specifications other than the long stroke that would explain the drop off?
Nice to see magazine coverage on Olds builds, but it is too bad that this could virtually be an article from 10 years ago if it didn't have a date on it.......
Oh look, another high dollar Oldsmobile big block build that makes just shy of 500hp and noses over completely before 5500rpm..... yawn.
I would be excited to see this exact engine build with some good dyno data from these tests, and then, when the new Edelbrock heads hit the shelves, updated with those new ones bolted on for some more testing.
After seeing how well 442Dude's 455 build with Edelbrocks and a stock aluminum W30 intake pushed power over 547hp with an even smaller cam and stock stroke crank..... 442Dude's build by VORTECPRO is the new high water-mark for me on moderately-cammed and Edelbrock-headed, purposeful street 455 builds.
Can you please elaborate? From the graph it looks like TQ is over 500 at peak HP which they stated was 488 HP at 5000 RPM. The graph does appear to show HP peaking closer to 5200, but even there, the TQ looks to be well above 450. And since HP = TQ * RPM / 5252, at this crossover point, it still looks like they’re about 480.
What I don’t understand is why the HP starts dropping off around 5400 RPM. Are you seeing anything in the specifications other than the long stroke that would explain the drop off?
I think the long stroke aggravates the problem along with inadequate cylinder heads to feed that size of engine combined with a possibility cam has lobes that don't like to REV. Stopping the pull at 5500 RPM doesn't help determine whats going on there either.
I think the long stroke aggravates the problem along with inadequate cylinder heads to feed that size of engine combined with a possibility cam has lobes that don't like to REV. Stopping the pull at 5500 RPM doesn't help determine whats going on there either.
Thanks! Your last point about stopping the pull at 5500 is interesting. To your point, something must be limiting the airflow or it is experiencing some kind of fueling problem.
It would be a fun Street motor and hard on tires. Unless you do a Rocket Racing block, a BBO stroker is massively under square. Unlike the 4" stroke SBO which is oversquare and apparently makes more power.
I have a few questions...
1. why would you build an engine that needs to be more streetable and then use a 106 LSA? Bad idle quality, lower vacuum...
2. Why the hell does this engine drop off so fast and so low? The 4.5 stroke and 4.185 bore is NOT inherently a bad configuration at all.
My 496 pulls well beyond 6200(I shift well below that)
Is it low lift? Bad head flow?
It’s a 106ICL, not a 106LSA.
There are lots of variables here. I’ve made 585/645 with a 495 and out of the box Edelbrocks. Trovato and others have done the same. Might be other extenuating circumstances. I can tell you the plenum on an RPM is actually smaller than a regular Performer. Therefore it’ll need more carb, spacer, something.
Last edited by cutlassefi; Oct 29, 2021 at 09:46 AM.
I have a few questions...
1. why would you build an engine that needs to be more streetable and then use a 106 LSA? Bad idle quality, lower vacuum...
2. Why the hell does this engine drop off so fast and so low? The 4.5 stroke and 4.185 bore is NOT inherently a bad configuration at all.
My 496 pulls well beyond 6200(I shift well below that)
Is it low lift? Bad head flow?
-peter
The head has no where near the cross sectional area it needs for 500 inches, so lets say it did have the cross sectional area maxed out (porting) which still isn't enough, then theres the valve size, this now becomes the choke point, ok so we put a bigger intake valve in there, actually how do we do that, theres a 4.185 bore, it won't fit, so making a Olds 455 with its 4.185 bore 500 inches IMO is a bad combination. I've always wanted to build a 425 my self, much more suited to production cylinder heads, and would certainly make more HP per inch. Question: Which combination has more TQ at the tire?
1. 500 HP @ 5700 RPM 580 TQ @ 4000 RPM with 1 to 1 final drive ratio and a 4.30 rear gear
2. 500 HP @ 5250 RPM 620 TQ @ 3500 RPM with 1 to 1 final drive ratio and a 3.73 rear gear
If your looking at peek numbers #1. What your not considering is the use of the engine. Peek numbers mean nothing. Now you just hit on a subject that you should expand on. Port designs. You can see in the published curve for the engine that the ports are too small or something in the valve train is wrong.
with 650 TQ that low it will have no problem moving the heavy boat it’s going in. The 236 int duration and .515” lift is why it’s signing off so early.. that’s really mild for 488 “
I’ll bet if they added 1.7 int rockers it would pick up 30+hp and TQ too.
