Building a stroker N/A budget 5K

[JMortensen]

"With this said, focus on good cylinder head portwork, good balancing on the rotating assy, match the camshaft to the head flowrates. It is also a good idea to get the intake ported to match the heads' flowrates as well....this way you have a strong, tuned powerplant with no weak links."

 

All that stuff was done. I gave my cam specs, and then port matched the intake myself to the head that Paul did. I have a "strong tuned powerplant" but apparently not as strong as others. This was tuned in my racecar with a wideband O2 and dialed right in to 12.8-13.2 under WOT. Not sure where else to go to let the ponies out. I guess it's at that "design limitation", albeit, others have surpassed my numbers with lesser motor. Wonder if it's that doggone MN47 head that I'm running.......might have to hog out one of my P90's and do a comparison.

If I were to venture a guess, I'd say cam or cam timing is the most likely culprit. Also remember that you shouldn't compare numbers with another dyno, they're all different and as Drax has pointed out you can get a dyno to read vastly different numbers with a little tweaking. You could do a 1/4 mile test and check your trap speed to get hp that way, it's at least independent of the dynamometer's inherent inaccuracy.

[Xnke]

I think Jon is right. All the HP left in the setup is in the tuning. You say you've dialled in your AFR's, but have you adjusted the timing? Recurved the timing advance to suit your motor and driving? Tried adjusting the cam one way or the other to see if you pick up any power?

 

There is a lot more than just fuel tuning to get the most out of an engine, it just gets overlooked as too hard or too minimal of a gain for a LOT of folks out there.

[luckygerman]

I'm thinking that you need to build a L28 without the stroker crank unless you already have the crank, you can get 2.9liters with an 89mm bore. My old friend who has is own machine shop and has been building anything from turbo 510's in the 70's to 2009's corvette z06's, the Datsun Head design is very difficult to make decent flow #'s because of its design. He has build a 3.1 for one of his customers last year and had to weld up all the combustion chambers so he could reshape them to make decent flow numbers. Well you never make your power in the Bottom end, it is all in your Top-end, thats why mid 70's buick 455's only made 180-200hp cause the compression Ratio and Head design. Turbos and Superchargers/Blowers can overcome poorly designed Heads.

 

For myself I will probably build me an L28 with Flat tops , 240z Head 11:1 Ratio and a nice Cam with Triples. If I can make 200hp at the wheels I will be Happy. You see, you can spend $3k to make a nice motor that will make 200-220hp or $6k total to make an extra 40-50hp on top of the motor you can build for half.

 

If you want more power you could build a 4.3 Chevy V6 with a Procharger

or use a RB25DE and cam it

or use a VQ35 from a 350z (300HP) 6sp tranny

[kce]

I don't know where you all are getting your machine prices...It was 120$ to have my block tanked, bored, honed, and magnafluxed; the head was 330$ to have it tanked, surfaced on three sides, milled .30 thousandths, new SI valves installed, and five-angle seats cut, and I had 80$ in tools/materials and 40 hours in the port job. Machine work does not have to be expensive, I'm not sure where these 5000$ stroker motors are coming from...the most expensive builds, perhaps; but a street motor? My complete engine build, including my custom manifold, TB's, and fuel system, totals up at just a little under 1500$.

 

Is machinework really that expensive in other parts of the world?

 

Yeah, seriously. I've never heard of machining costs over $500 dollars and I live in Alaska where it cost at least 30% more for ANYTHING. I think we've paid around $400 for having a block tanked, all the plugs punched out, bored, honed and the cam bearings pressed in. When you guys are quoting machining costs of around $2000 what are you including? Head porting, balancing, assembly? Any chance you could be more specific? Because $2000 for machining cost just sounds outrageously expensive for a street engine.

[d3c0y]

Also when talking about forged rods - wouldnt brand new lighter weight units be better than a 30 year old fatigued set?

At $350 - $600ish for a new set of rods with ARP bolts (well the ones im looking at anyway) the prep on a stock rod + fastners would have to be close to costing that much?

[Tony D]

I think that $5K Budget is right in line with a Rebello Engine Long-Block...but you would have to ship it.

[kce]

I think that $5K Budget is right in line with a Rebello Engine Long-Block...but you would have to ship it.

 

I hate to resurrect a thread but I figured that doing so was preferable to creating a whole new one.

 

I'm sorry if I'm being an idiot but I could only find the 3.0L Stroker reciprocating assembly listed for sale on Rebello's website. Do they also sell a whole long block kit? How would such a kit compare to just using a LD crank, L24 rods, and KA24 pistons? The Rebello Stroker Kit is listed at $1,800 which doesn't sound too expensive considering everything is included, but I imagine shipping adds a lot to it (I can'tell from their website but it appears that you have to send in your crank as a core exchange?).

 

Hypothetically speaking, if I had a 5K budget for an engine, would you recommend the Rebello kit over the DIY combo? What kind of rough, back of the napkin horsepower numbers do you think a moderate 3.0L could produce with a street-able cam and no head work? I've seen numbers all over the forum starting at 190hp and ending somewhere up at 290hp! (Of course, I know you can't just compare HP numbers straight across because of all the variables involved - I'm just looking for estimates).

[kce]

Double Post...

Edited November 30, 2010 by kce

[ktm]

Hypothetically speaking, if I had a 5K budget for an engine, would you recommend the Rebello kit over the DIY combo?

 

Only if you really, REALLY want a stroker. There are other choices out there with significantly better power return for your dollar.

 

What kind of rough, back of the napkin horsepower numbers do you think a moderate 3.0L could produce with a street-able cam and no head work? I've seen numbers all over the forum starting at 190hp and ending somewhere up at 290hp! (Of course, I know you can't just compare HP numbers straight across because of all the variables involved - I'm just looking for estimates).

 

Power is in the head. With NO headwork, only expect around a 7% increase in power over a stock L28 everything else the same. Given that the compression ratio will most likely increase, you will probably see more than 7%. However, you really need to have the head ported, a matching cam, and the right induction and fueling to make power.

[kce]

Hmmm. So assuming stock horsepower is somewhere around 150hp on the L28, increasing the displacement alone might net 10-15 extra horsepower... but with a better cam and induction would numbers somewhere around 250hp be achievable for 5K?

 

Maybe I should ask the question the other way around. If you had a 5K budget to build a naturally aspirated 3.0/1 Liter L6, how would you go about it? Sparing any heroics, would 250 or 275hp be attainable? From my flailing around the forum these kinds of results seem possible, but are certainly not the norm (as you pointed out there are better and more productive ways to spend 5K on L6).

 

In my dreams, I would love to build a 300hp 3.0L that's naturally aspirated. I'm just wondering what kind of price tag would be attached to that kind of engine and whether my commitment to a 3.0L would be enough to overcome it.

 

 

 

And I will repeat the mantra

You can have slow, reliable and cheap.

You can have fast, unreliable (err, broken) and cheap.

Or you can have fast, reliable and expensive.

Edited November 30, 2010 by kce

[Gollum]

If you just build it yourself like everyone is saying, with a machine shop prepping the block and a specialist porting the head, I can see you reaching over 250whp and coming in under budget.

 

But the key, as it's been stated, is being frugal. The crank and rods are out there, in the junkyards, waiting to be saved. The only big ticket item for the bottom end would be pistons, and you'll want them to be fairly lightweight.

 

Something that hasn't been touched on, and the only real reason I'm posting, is that you mentioned going EFI. I'd advise against this for a budget build. The stock EFI intakes don't breathe well top of the RPM range, and a custom manifold or itb's combined with the price of injectors, ECU, ect just makes for a whole elephant of a problem to overcome with the budget. That can easily be a $1,000 decision. Just stick with carbs, even though there's plenty of reasons to hate them. They work, they're simple, easy to find, and affordable.

[kce]

Thanks for your reply. I'm definitely planning on doing the work myself (that's part of the fun!) and it's not the first engine I've built so I have some experience with the process (although with a different engine). I'm also not adverse to taking my time buying affordable parts. I just wanted to know if my goals were at all realistic or if my enthusiasm was getting the best of me.

 

The EFI vs. carburetors is hard choice for me. On one hand, I love the mechanical look, feel and sound of carburetors (not to mention their affordability compared to EFI). On the other hand, it seems pretty hard to argue with the technical merits of a well-tuned EFI system; it is just so expensive... (new tank, pump, lines, filter, pressure regulator, manifold, injectors, ECU, etc.). Anyways, it is kind of a smaller version of my LS1 vs. L6 debate. Choices, choices.

 

I suppose I need to do some more research...

[kce]

I suppose I need to do some more research...

 

Here's some recommended reading for anyone in my shoes who is following along:

 

NA 3.1L

Way more than you ever wanted to know about L6 Cylinder Heads

L6 Cylinder Head Descriptions

Japanese NA 3.1L - 400hp

Edited December 4, 2010 by kce