Hi-comp 2.4S or 3.x????

[randywebb]

To placate Randy’s concern, ...
- only placates me if I don't travel very far from home!

Also, if you live in the PNW, the Rubbermade solution is free for 6 months every year.

[Grady Clay]

Randy,

I guess if the current NW deluge continues you will have the "Deep Tread" award for the winners. (I wonder what the "flotation" is for the current track tires? - HeHe).

We are way ahead for the ski areas; all are open early and this may be one of the best snow seasons ever. That still seems to be a secret so if any Pelicans want to ski Colorado, let me know. Randy, you could send some of your excess moisture to us on the "Front Range." We are having "SoCal" weather here in Denver every day.

I did a late anylisis of the Rubbermaid Solution in high humidity situations and showed that it still worked great. It is such an inexpensive and effective solution for track use everyone should be using it.

Best,
Grady

[Briana]

Originally posted by BK911
This is for a DE/AX car and maybe an occasional trip around some back roads. I am not concerned with race classification at this point.

If you were me, what would you do?

I'd sell the 630xxxx engine complete. Take the proceeds and buy a 3.6 and call it a day.

[BK911]

Ladies - Gentlemen, I appreciate all the input. I like the idea of using a mag case as a base so it looks stock-ish. But I also like the idea of the 3.6. I change my mind a bit, but now I am leaning towards selling the S motor and picking up a 3.x. I guess whichever I can get the best deal on the best motor for. What's the weight difference between the mag cased engines and the various 3.x's?

I was also considering taking this car back to stock, sell it, and then pick up a 74 - 77 for a track beast. I just put so much work in this car. Everything in it is brand new or rebuilt with the track in mind. Thanks to the Rossi book, I just bought fiberglass bumpers and a ducktail. So a $20 book has already cost me over a grand, and I'm not done yet!

Scott: If you're talking about your E, I would put an E engine back in it. I currently have a hi-comp 2.4E in the 73 and it is a really sweet engine. I 'need' to build a -6 for my 914, so I figured I'd just use the E and build/buy something faster for the 73.

[pieterk]

Grady, you never cease to amaze. Thank you!

Your detailed comments had exactly the effect I'd hoped for, which was to help clarify the more essential differences between the two in terms of practicality. I have no doubt that both offer awe-inspiring experiences, but now it's clearer to me that the 2.8S really would be the way to go for me, especially because the idea is that this would be a slow build that would happen in the background on a donor motor as I continue to drive the car with the 2.7RS. The 2.8SS seems a LOT more daunting in terms of getting it right and sourcing the correct components. The idea of having to 'only' buy new P&Cs, cams, twin plug hardware, and paying for machining and adjusting the MFI seems more manageable for someone like myself than building the 2.8SS. If I were to do this, I would make sure to start correctly, with a good case, get it reconditioned, shuffle-pinned, balanced, etc. I'd rather spend more up front and make sure it's absolutely correct than half-ass it.

Also, the weight is an issue for me. I'm not in radical pursuit of weight loss at all costs, but it's pretty high up the scale for me, and this would help keep the rear light(er). I suppose that if the project were to take as long as I imagine (two years plus or minus?), that would make it more possible to purchase and install as light as possible parts, where the choices exist. Things like titanium rods would no doubt be just too expensive, but little things like titanium fasteners for a glass shroud and other such things are doable.

I don't recall seeing the idea of a 13:1 CR in all of your previous posts. Wow. That would be something else!

To re-address a point of yours from previous posts, can you confirm that even with a CR as high as 13:1, as long as you were to keep the revs limited at say 7,300-7,500, could you reasonably expect such a motor to have a long life without requiring frequent refreshing? If 7,300 is too high, what would be the highest you recommend? I pick that number only because that's where my 2.7RS revs to, and so far it's fine.

As for lightening the back end, my decklid is fiberglass, as are the bumpers, and the license plate is held on with the barest of brackets. No frame. Short of drilling, and glass tail light housings, I'm not sure what else I can do to get weight out of the back. Maybe shave the decklid underneath? Remove or trim the grill?

Finally, I think the Rubbermaid Solution is starting to sink in! I'm going to think about pulling that together early next year or in the spring, when it starts to get hot here again.

Are you on a PC? If it's a Mac, I might be able to help. Let me know.

Thanks again Grady; incredible stuff. If I make it to Colorado on a road trip, beers on me!

[randywebb]

Grady - the current NW deluge has moved on towards you - the storms continue with a new one next week. This is nothing like '96 tho.

I can probably help with your comp. if it's a PC. Also if you have Google search running, remember that it never loses things that were ever on the PC...

Pieter - CF deck lid & bumpers will be lighter than FG; lose the internal hinges for ext. R type ones; mesh screen to replace decklid grill; rubber hold-downs to replace latch mechanism -- nothing big.

I will post savings if I get a chance on another thread...

[pieterk]

Randy, what kind of mesh screen are you using or would you suggest? Got any pictures?

CF: okay. Do you know how much of a weight difference we're talking about? That's good to know for the long run, but buying CF replacements for FG parts isn't something I'd pursue at this moment.

I don't have the latch on anymore. I've got a single centered hood pin installed where the latch used to be. It's not as light as the rubber, but it's lighter. No struts anymore either; instead I've got one of the CF Seine supports. It weighs grams. Pretty neat, and it works.

I'm still waiting to see what Steve Weiner cooks up as aluminum replacements for the rainguards. My interest in them is not primarily in weight savings, but rather, air flow, but the pound or so lost won't be begrudged!

[randywebb]

a few lbs. for CF - you need to find out the wts. of what you have now vs. autoclaved CF parts -- I discovered my FG lid (which fit like crap) is unusually heavy. I'd like to strangle the seller...

mesh can save ~2 lbs. - I have the original strakes on my car (painted silver) but mine is a street car. There are pics on the Early 911s bbs and you can search here.
Try mesh + grill + deck + lid -- see what you get or same w/ decklid instead

I'd get Aluminum hex punched mesh and put a rubber weatherstrip around the periphery - could also use woven wire but won't look as nice -- also look up pics of Rob Dickenson's car - he use Lexan with holes in it - prob. heavier than the mesh.

if you have a ducktail you can remove it - tho you obviously won't get as good a flow regime at higher speeds

[dd74]

So I'm a little confused. Is it recommended or not to use the 2.7 as the basis for a 2.8 or 2.9 project. I've been giving this some thought with my own 2.7.

So what P/Cs will I need? I imagine I should twin-plug the heads? Should stock intakes work well enough for a 2.8 or 2.9 upgrade?

[pieterk]

Funny, I spend so much time using the search function and researching on this site, and sometimes, the brain just switches off and I forget that option exists for the simplest things!

Thanks.

I remember seeing the Lexan grill. Pretty neat.

I've got an idea combining a very light wire mesh painted black with possibly thin aluminum or plastic straps/braces acting as supports for the mesh between the mounting holes, which would cover the small triangular mounting tabs. I really don't like the look of the deck lid with those tabs exposed and just a thin mesh, or worse, no mesh at all, as I very occasionally have seen.

[randywebb]

post it when you do - we all loove pics

[Bobboloo]

Originally posted by dd74
So I'm a little confused. Is it recommended or not to use the 2.7 as the basis for a 2.8 or 2.9 project. I've been giving this some thought with my own 2.7.

So what P/Cs will I need? I imagine I should twin-plug the heads? Should stock intakes work well enough for a 2.8 or 2.9 upgrade?

Dave,

The 2.7 is a good starting point. The main advantage of starting with a 2.4 is, that if you plan on using MFI, the 2.4 motors up to 73.5 already have the heads tapped for the injectors. If your planning on using carbs then a 2.7CIS motor is a good starting point.

The stock intakes on a 2.7S motor will already have the right port size. (36in 35ex) The 2.7 "normal" motors however need to be ported for use with an S cam.

For P+C's you can go with 90mm cylinder cores bored out to 92mm and plated with Nikasil Then buy some JE 92mm pistons to put in them.

If you've got the extra bank then you can buy a new set of Mahle 92mm P+C's (RSR).

It's best to stay away from the 93mm 2.9 conversion. The cylinders walls are too thin and considering you like to track the car sometimes they are not a good choice. You get blow by from the cylinder flex.

Twin-plugging is only necessary if you go with high compression and still use pump gas. You can run 9.3:1 with premium and not need twin plugs. If you go above that you'll need the twin plugs.

[gumba]

I see some contraditions with 2.8 s & ss vs reliability. One of the cool factors seems to be they will wind up to 8,000-9,000 rpm. But most engine builders suggest that for long life you should be shifting at 7,000-7,500 rpm. Is there a cam that makes these motors come alive at the lower rpm where they are typically driven on the street? Even at the track I don't think you want to make 8,000 + shifts a common practice.
My old 2.8 twin plug w/250 hp didn't come alive until 4500 rpm (w/ 906 cams) and pulled strong to around 7500 rpm. I occassionally drove the car on the street but could rarely wind it out. I'm not trying to dissuade anyone but there are some trade offs to consider. I had started to gather the parts up for a 2.8 ss being lucky enough to find a nice 3.0 turbo case (now sold) but decided to go with a 3.4 twin plug. A 2.8 s or ss mfi motor is a very cool thing.
2.8 twin plug on '73S case, 906 cams, 46mm webers, ect. 255 fwhp. (gone)
3.4 twin plug, DC 80 cams, 46mm webers, guessing around 300 h.p.
3.5 twin plug turbo street motor nearing completion.

[dd74]

Originally posted by Bobboloo
Dave,

The 2.7 is a good starting point. The main advantage of starting with a 2.4 is, that if you plan on using MFI, the 2.4 motors up to 73.5 already have the heads tapped for the injectors. If your planning on using carbs then a 2.7CIS motor is a good starting point.

The stock intakes on a 2.7S motor will already have the right port size. (36in 35ex) The 2.7 "normal" motors however need to be ported for use with an S cam.

For P+C's you can go with 90mm cylinder cores bored out to 92mm and plated with Nikasil Then buy some JE 92mm pistons to put in them.

If you've got the extra bank then you can buy a new set of Mahle 92mm P+C's (RSR).

It's best to stay away from the 93mm 2.9 conversion. The cylinders walls are too thin and considering you like to track the car sometimes they are not a good choice. You get blow by from the cylinder flex.

Twin-plugging is only necessary if you go with high compression and still use pump gas. You can run 9.3:1 with premium and not need twin plugs. If you go above that you'll need the twin plugs.

Bobby - the motor I have already has the Webers, has stock 36/35 port sizes and 10.8 compression. No twin plugging, though I'm thinking about it as gas seems really bad lately.

The cam selection keeps it from too much rattling (detonation?) which are Web Cam 120/104. Nonetheless, even with this cam, when the motor is hot and has been tooling around in the city, I've found you can't just step on the accelerator WOT without some upper-RPM detonation. Hot and at the race track, the motor is fine, but in city traffic, it complains a bit when stepped on. I've found on the street, you have to wind the engine out little by little to redline so it won't rattle. At Willow, where I use a race gas blend, there's no rattling to speak of.

The funny thing is my old 3.0 with 9.3:1 compression, rattled in the same way. When hot, and just tooling around on the street, step WOT on the throttle and from 5,000 to 6,500, it rattled, no matter how the timing was adjusted.

In the end, with both the 3.0 and 2.7, I suspect it to be hot cylinder heads more so than compression.

The 3.0 I used for three years, and it ran strong and hard up to when I traded it for the 2.7. I expect the same three-year run and longer from this beefed up 2.7, which to date is a year old. I simply find you just can't trounce on them when they're hot if you want to reach red line. When cool and in cool temperatures, they'll take all the abuse possible. Hot weather is a different story.

But to be sure, if I had to do it all over again (I bought the 2.7 and 3.0 already assembled) - I would twin plug the 2.7. Given the chance I might do that in a couple years, I may as well give it some oomph and punch it out to a 2.8, which is why I ask how difficult it is to complete such a project.

I bought an M&K muffler and will have TRE install it. I'll let Dave, et al, fool around with the timing and jet the carbs a bit if needed, and see from there.

[dd74]

Originally posted by gumba

My old 2.8 twin plug w/250 hp didn't come alive until 4500 rpm (w/ 906 cams) and pulled strong to around 7500 rpm. I occassionally drove the car on the street but could rarely wind it out.

I would have used the WebCam 120/104. My 2.7 revs above 7,300 and feels as if it has as broad a torque spread as my old '83 3.0, which had more torque than older 3.0 variants.

[YTNUKLR]

Any heads can be machined to work w/ MFI, it's a simple and relatively cheap operation to convert 2.7 (CIS) heads to MFI.

92mm RSR 2.8 Pistons and Cylinders are $3,500+, maybe even $4,500....lotta dough.

I am building a 2.8SS for a PCA race car right now, a similar engine to Henry's. In the end, yes, admittedly it's more of a pain in the a$$ to get the parts together for this, as opposed to a 2.8 "S", and it takes longer. BUT, after the extensive machining a mag case requires, and the RSR pistons and cylinders, the monetary cost is not far apart at all.

Personally, I find the 2.8SS to be more attractive because you can easily run 49/41.5mm big valves (same as the original 2.8RSR) whereas with the 2.7/2.8S, you typically use 46/40mm valves. Also, it uses easy-to-find 3.2 Nikasil cylinders ($400 /set?) & JE pistons ($800), standard 3.2L 95mm Goetze piston rings, etc. The 66mm crank allows it to wind harder with less vibration, giving a nice wide usable range from 5500-8000+. Durability is also a factor; the case is aluminum, and thus, perhaps only 10% stronger than a mag case, it does not deform like mag does, its fatigue tolerance is much higher. Also, one can use the 4-bearing cams with the increased base-circle diameter, allowing for smoother progression of power on-throttle. Henry has demonstrated that 112hp/L+ is easily attainable, even surpassing the original (finicky) 2.8RSR, whose specific output was "only" 110hp/L.

Brian: for my '70E, I have the original engine, which needs a rebuild. E power is great, I confess, but there's something indescribable about 7500 rpm--not what the E is. Someday I WILL put the 2.2E back in place, for now it will probably be a 2.4S-spec. hot-rod. Or 3.0L.

Cheers
Scott

[Bobboloo]

Originally posted by dd74
Bobby - the motor I have already has the Webers, has stock 36/35 port sizes and 10.8 compression. No twin plugging, though I'm thinking about it as gas seems really bad lately.

Your motor is a diffenent candidate for twin plugs. My 87' Euro 3.2 motor has the same problem with pump premium. Fortunently there is a gas station near my house that has 104 octane gas. I put in 2 gallons of 104 with each fill up (16 gal. US tank) and the detonation under heavy throttle went away. If you have the later style 22 gal. tank you may want to put in more 104.You should consider doing the same until you either twin plug or re-curve the dizzy to stop the detonation. Re-curving the dizzy will rob power from the top end however which is not a pleasant thing and not really an option IMO.

The station is called Ultramax. It's on the corner of Sherman Way and Woodley.

2.8L is nice but really how much different will it be than a comparable 2.7 i.e. same cam and CR. The higher CR is what makes these 2.7/2.8 motors more punchy. It improves the low end torque.

[dd74]

Originally posted by Bobboloo
Your motor is a diffenent candidate for twin plugs. My 87' Euro 3.2 motor has the same problem with pump premium. Fortunently there is a gas station near my house that has 104 octane gas. I put in 2 gallons of 104 with each fill up (16 gal. US tank) and the detonation under heavy throttle went away. If you have the later style 22 gal. tank you may want to put in more 104.You should consider doing the same until you either twin plug or re-curve the dizzy to stop the detonation. Re-curving the dizzy will rob power from the top end however which is not a pleasant thing and not really an option IMO.

The station is called Ultramax. It's on the corner of Sherman Way and Woodley.

2.8L is nice but really how much different will it be than a comparable 2.7 i.e. same cam and CR. The higher CR is what makes these 2.7/2.8 motors more punchy. It improves the low end torque.

Yeah - I'm not recurving anything, so I guess my fears have been realized: race gas for street driving

Fortunately, out in Sun Valley, there's a place that sells it by the ten-gallon can. Either that or Ultramax, as you suggest.

Oh well, better than blowing up my motor.

[pieterk]

dd, check around more. I think there are several stations in the valley that sell 100. I'm especially lucky in that there's a 76 an easy ten minute shot up the 110 from me that has it; it's across the street from the end of the freeway, on the corner at the light, where it becomes Arroyo Parkway. Another reason to live off the Arroyo!

[dd74]

Originally posted by pieterk
dd, check around more. I think there are several stations in the valley that sell 100. I'm especially lucky in that there's a 76 an easy ten minute shot up the 110 from me that has it; it's across the street from the end of the freeway, on the corner at the light, where it becomes Arroyo Parkway. Another reason to live off the Arroyo!

Yeow! Drive all the away to Pa-sa-de-na for gas? The only reason I'd go out there for pleasure is to see the Trojans (who will play in the Rose Bowl).