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Street Sweeper pre-build

7228 Views 39 Replies 12 Participants Last post by  madhatterpdc
This post has a couple different intentions. Primary, is to post my planned motor specs and expectations and recieve feedback from the community. Secondary, is to recruit recommendations for suppliers for the necessary outstanding components.

The Street Sweeper name just came to me as I was trying to find a subject for this thread. Expectations include a motor that can provide enough juice so that the GT can keep up (150 -175 HP), retain at least a little bit of streetability (to get to and from cruises and the track). It must rev quickly, and run on 93 octane (the best available in the area). A 5-speed conversion will be installed from OGTS with a lightened flywheel and S-10 clutch. Handling will be probably be addressed with 1.5" lower springs, Koni reds and OGTS sway bars. Braking will more than likely be the big stuff from a '75 Manta.

But the motor is what is important in the nearest future. Items that I have on hand include:
- a good block already torn down with minimal wear
- stock crank is in good shape
- Dual side draft manifolds with dual SK DCOE 40's
- a built head, specs include
-- Cam: .488 lift, 295 adv duration (262 @ 0.050), 110 lobe center
-- Valves: 44mm intake, 35mm exhaust, with 11/32" stem size, tapered at seat
-- Titanium springs and Deep titanium retainers (remember the deep part for a later question)
-- RallyBob/Samdog Roller Rockers with stud girdle.

Parts I am not sure about what to choose, where to find,
- 11:1 compression ratio pistons, 3.74", Venolis vs. Arias vs. other?
- 2.2 vs. 2.0
- if 2.2, then should I start the search for an Opel 2.2 crank or have my 1.9 crank stroked
- recommended supplier of flat titanium retainers that don't interfere with roller rockers.
- are the dual 40's going to be "enough" for the RPM's that the cam require

Does anyone out there have parts that I am looking for (crank, pistons, retainers). My preference is to purchase from other OGT.com members, then OGTS, then direct from suppliers.

Any insight, recommendations, corrections appreciated.

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I will look to see if I have pistons and other bit but it will be a few weeks until I can get to it. Rally Bob is on vacation...I'm sure he can help with engine recomendations....until then, you can search posts by Rally Bob in the archives for ideas
Thanks Gregg, I appreciate you taking a look whenever you have a chance.

I have scrapped the 2.2 idea. The more I thought about it, the more I realize that "quick revving" and "stroked crank", are counterintuitive.

Those that have built race motors probably want to stop reading here, unless you would like to edit my math (something I always appreciate).

I am looking for a motor that revs and gets to the power curve quickly. A lightened and balanced crank, rods and flywheel will go a long way towards making that happen. But, if a motor were to have a stroke that were 7.5 cm (0.30" or 11%) longer, the piston would have to travel roughly 11% quicker to cover the added distance in the same amount of time. At my projected redline of 7500 RPM, the 2.2 stroke exceeds acceptable piston speeds (3500 FPM).

1.9/2.0 Stroke = 2.75", 2.2 Stroke = 3.05", difference = 0.3"

Piston Speeds at 7500 RPM
1.9/2.0 piston speed = (2.75" * 7500rpm)/6 = 3437.5 fpm
2.2 piston speed = (3.05" * 7500rpm)/6 = 3812.5 fpm

Max RPM for stroke
1.9/2.0 max rpm (3500fpm * 6)/2.75" = 7636 rpm
2.2 max rpm (3500fpm * 6)/3.05" = 6885 rpm

Remember that the "max Piston Speed" of 3500 fpm is a fairly conservative number. High-quality, perfectly machined, forged, lightweight components (read: full race high cost) can exceed 5000 fpm. That would be 11,000 rpm on a 2.0 or 9,800 on a 2.2, but that's not off-the-shelf stuff. RPM calculations based on formulas above, only apply to the lower end. The valvetrain must also be up to snuff. Make sure that springs, rockers, retainers and bearings are adequate.
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go with a 2.2 you will be a very happy camper

Gil used to sell them for around $1300 been awhile

Rally Bob did a write up on a 160 HP 2.2 buildup maybe some one has a copy

A stock 2.2 crank is in fact lighter than a 1.9 crank, and as a result they usually rev a bit quicker.

A stock 2.2 crank can handle 10,000 rpms. I used to race one at 9400-9500 regularly. But it did have 7/16" ARP flywheel bolts and two dowels added, at that rpm the flywheel is trying hard to get away from the crank!

Stock Opel rods, properly prepped (polished, shotpeened, lightened a bit, ARP bolts) can take 8500 rpms with a 1.9 or 2.2 crank, and at a surprisingly long time at racing speeds. I suspect for street use that equates to a lifetime of driving.

That cam you've chosen should be good for a powerband between 5000-8500 or so, assuming the head is breathing well.

However, the carbs you have can't breathe that well with that cam, so I suspect your true usable powerband will be closer to 4500-7500 or so, with the power falling off fast at higher rpms.

Your key concerns will be valvetrain reliability, and having the proper spring rate. Above 8000 rpms, I consider a set of new rocker studs, roller rockers, and a stud girdle essential. Above 8500 rpms it is suicide without these parts!

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Thanks for the information. I have mentally reset the projected redline to 8000 rpm. Giving a 2.2 a piston speed of just over 4,000 fpm. Definitely need everything balanced, shot-peened and ARP wherever possible. I am now begining the search for a 2.2 crank. Just to make sure, the 2.2 crank does fit in a 1.9 block correct?

Next question, what size choke tubes are necessary? A 2.2 is 134 CID, at 8000 rpm that calculates to a theoretical CFM of 310 CFM

Theoretical CFM = (RPM x Displacement in cubic inches) / 3456
Street carb CFM (assumes 85% volumetric efficiency) = Theoretical CFM x 0.85
Racing carb (assumes 110% VE) = Theoretical CFM x 1.1

For this application, the necessary chokes would need to flow in the range of 264 CFM (street) to 341 CFM (racing). How do I correlate CFM to choke sizes?

Apologies for all the calculations and figures, but I thought it might be helpful for future reference if all calculations were inserted as part of the thread.
Yup, the 2.2 crank fits all the other CIH blocks. Same bearings, etc. Only important difference is the crank pulley attachment bolt is larger in diameter, so try to get that as well. Pulleys are interchangeable however.

Don't worry about the CFM ratings. Heads are flowed at a different value than carbs, and even 2 bbl vs. 4 bbl carbs are rated differently. With IR (individual runner) induction systems, these formulae do not apply anyway. You should be able to run 36 mm venturis, which are the largest that fit a 40 mm Weber. I've run 36 mm venturis with the larger 45 DCOE's on (very) streetable 2.2's and there was no shortage of torque.

In 'theory' a pair of 45 mm DCOE's with no choke flow over 880 cfm, yet a well-built 2.2 litre performance engine can still handle 48's.

Even in my circle-track days I found more power with a 500 cfm Holley that was modified to flow 640 cfm. Even though 'in theory' it only needed about 330 cfm.

So you should go with essentially the biggest carbs you can fit on your engine to compliment that camshaft. You'll love it.....:)
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Gill had a 2.2 crank that I was able to pick up cheap. It's as-is, which is fine because I planned on having the whole rotating assembly lightened, cleaned and balanced once I have everything. This motor will be fed by a set of 45's. It probably would have run okay with 36mm chokes, but that being the upper limit for 40's, the inevitable experimentation with larger chokes would have been impossible.

My next biggest stumbling block is pistons. I'm waiting to hear back on a couple of queries to see if there are any sets of 11:1, 3.74" (or close) available. If not then I am going to have to have a set made. I had a conversation with Arias and they quoted me $140 per cylinder with rings. Not terrible, but far from cheap.

I am really hesitant to say this out loud, but... Is there enough interest for a possible group buy of high compression (domed) pistons?
wow you scored a 2.2 crank -- good for you

i would try to go for flat top pistons
you really have to have your act together with Pop Up pistons in an Opel

CR is not every thing try to shoot for a 6500 rpm torque motor

what ever you get about 6500 rpm will be cake

i picked up some nice rods awhile back and they came with Ross flat top pistons
they say ross375 on the underside

The rest of your specs look pretty good except the Cam and maybe the koni reds.

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Have a look at www.kb-silvolite.com

305 Chevy hypereutectic pistons come in three pin heights 1.5610" std;
1.4330" stroker; and 1.2610" for use with 6.0" rods in a 305.

The quality is excellent and you may be able to use a suitable aftermarket conrod - or even 2.4L Opel ones - I'll leave the rod length calculations to you.
Could even get away with the stock ones with centre to centre modifications as the pin hole has to be opened out from .906" to .927" for the chevy pins .... ??
After some extensive consideration, and exasperation, I think that I am going to have to go with flat-tops. I am not ecstatic about this, but I really think that I am going to save myself a lot of aggravation of trying to locate domed pistons (unless someone comes through with a last-minute hail mary set of 11:1 pistons).

This means that I will also have to go with a smaller cam, and I am open to suggestions

So that means the current parts on hand for this motor are:
- 2.2 crank
- Dual side draft manifolds with dual SK DCOE 40's
- a built head, specs include
-- Valves: 44mm intake, 35mm exhaust, with 11/32" stem size, tapered at seat
-- Titanium springs and titanium retainers
-- RallyBob/Samdog Roller Rockers with stud girdle.

Major parts needed:
lightened flywheel

Parts for sale:
Cam: .488 lift, 295 adv duration (262 @ 0.050), 110 lobe center
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I've been quietly trying to find an affordable throttle body injection set up for that would fit on a set of dual side draft manifolds. Does anyone know anything more about this setup:

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Did you look into Jenvey? They have some of the more affordable throttle bodies, but still not cheap.


I had found a company in Australia a few year back that was cheaper than the Jenveys but the last time I tried to find them again, I couldn't:(

Have you considered using a standard '75 manifold or possibly even cutting down a 3.0 manifold as many have done in Europe? It has a larger runner cross section for better flow. Just some thoughts...

Yeah i know about them I have 2 sets

Those are Toyota 1.6 liter, 4AG, 20V (20 valve) Quad Throttle bodies.(the motor is rated at 165HP so a lot of people are importing front cuts and replacing there old 4age motors)

Those ones have been put on a custom manifold with extensions so they will work on a Toyota 3SGT (MR2 second Gen.)

i been goofing around with some in fact i just posted these pic earlier tonight on the MR2 forum

They are a pretty neat factory part. Each TB is individual with its own spring so it wouldn't be to hard to change the spacing.

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Wow, I finally sat down and did some more calculations on my motor, and I have proved to myself that you should always do your homework before you start running your mouth. I have been hunting valiantly for some domed pistons, trying to attain a compression ratio of 11:1 to overcome the significant valve overlap of my cam and the poor off-idle qualities of the dual side draft configuration. Well, I let my calculations do the talking.

Chamber volume = 52.1cc (as quoted from Bob for a stock head, I anticipate my head being a great deal different as I have larger valves and mild decking, but this is a good starting point).

Gasket Volume = 6.876cc (again, a very generous assumption, but a good starting point)

Swept volume (for 2.0 pistons and 2.2 crank, assumes TDC flush with block) = 549.34 (Pi/4*Bore*Stroke or known displacement in cc's divided by 4)

Compression Ratio = (Swept Vol + Chamber Vol + Gasket Vol) / (Chamber Vol + Gasket Vol)

CR = (549.34 + 52.1 + 6.876) / (52.1 + 6.876)
CR = (608.316) / (58.976)
CR = 10.3:1

For giggles I calculated out what the CR would have been had I actually installed domed pistons (assuming a dome volume of 12cc)... 12.7:1, say bye-bye to pump gas.

aw crap, I just went through all these calculations and I forgot to take into account the ring land. It's 3 am, I need to go to bed, I am probably going to go back and edit this post in the morning (afternoon?), but I am interested in hearing what everyone else to say either way. Either way, most of these numbers are next to useless for me until I properly CC my head. And then there's the half point reduction for fly cutting the pistons.

If sounds like I'm frustrated, I'm definitely not. I really enjoy this stuff It's just late and I need to go to bed.
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Calculated, static compression ratio does not take into account the closing point of the intake cam lobe or other variables that affect the compression that the motor "sees" when it is actually running. That is why Dave ("Nobody") has been able to utilise a CR of near 11:1 on pump gas by installing a suitable, long duration cam (As RallyBob so rightly said could be done!).

Have a look at www.kb-silvolite.com and see their Tech articles on "Dynamic Effective Compression Ratio" and also the compression calculators that are on that site. All extremely interesting and puts a whole new light on CR's
Valve notches can add up to a lot, I just cc'd a piston top and the valve reliefs were 5.8 cc's! Sure takes a bite out of the compression ratio.

Static vs. dynamic CRs . . . my recent build-up

GTJIM said:
Calculated, static compression ratio does not take into account the closing point of the intake cam lobe or other variables that affect the compression that the motor "sees" when it is actually running. That is why Dave ("Nobody") has been able to utilise a CR of near 11:1 on pump gas by installing a suitable, long duration cam (As RallyBob so rightly said could be done!).

Have a look at www.kb-silvolite.com and see their Tech articles on "Dynamic Effective Compression Ratio" and also the compression calculators that are on that site. All extremely interesting and puts a whole new light on CR's
Taking cam profile into consideration when estimating (calculating) dynamic CRs certainly helps explain why my 10.7 CR, domed piston, large valve, stroked engine runs on 87 RON without any pinging or resorting to retarded ignition. ;)

Brief specs:
'72 ported head with 45mm Opel intakes, 38mm Opel exhausts, 224°@.050"/.465"/110°LDA cam/solids, matched Opel single springs, 8 Opel intake retainers (lighter) and valve locks, rockers and lock-nuts from my 2.4.
'71 (stationary pump) block bored to 3.701", forged 94mm Venolia pistons with .100" domes, moly top rings, no-gap seconds, 3-piece oils, stock '71 forged rods bored for .912" Ford LW pins, .010"/.010" 2.2 crank, everything "zero balanced".
'73 timing cover with new timing chain and tensioners, OP relief spring tensioned 2mm additional.
'75 distributor with locked, mechanical only advance and Pertronix, advance weights resprung, set at 10° initial, 35° total all in at 3000RPM, 6500RPM rev-limiting Bosch rotor, MSD5 multispark, Bosch "red" coil, Bosch WR7BP plugs at .040" (1mm).
Steinmetz SSD welded and ported (48mm) intake, single DHLA48 carb with 15mm trumpets inside fabricated cold-air plenum, filtered by K&N 78mm filter.
Old style, 4 into 1, HT coated header into 2.25" exhaust, turbo muffler and gutted "stock", twin-pipe resonator.
Remote oil filter and T-stat controlled "Volvo turbo" oil cooler.

Result: Street sweeping TORQUE MONSTER! :D
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Let's see, I went back and re-read my post. I also read everyone's replies and appreciate all the good information. My first question is,

does 10.3:1 make sense for a 2.2 with flat-tops (ignoring valve notches and assuming stock head)? In other words are my calculations even close.

Otto, your post states that your domed pistons have a dome of 0.100", by my calculations, you have a dome volume of approximately 2cc, is that correct?

how much volume does the ring land add?

I will also be seeking out a burette today... I knew that pharmacy degree would come in handy some day. Also, I need to stop doing all my calculations at 3 am.
Dome CRs

I thought it was a bit more than just 2 cc. R-Bob calculated 9.5CR for 94mm flat-top pistons with the 2.2 crank and a 1.9 head, and 11.1CR with .150" domes. I had the domes milled .050" (.100" domes) and extrapolated the CR from there mathematically by calculating volume of material removed. Couldn't locate my numbers, but it came to ~10.7CR.

With the small overlap cam I'm using, it's probably a bit lower when dynamically measured . . . perhaps ~10.3CR. With this engine's long stroke (77.5mm), it produces awesome torque from ~3000 to 6200 RPMs . . . EXACTLY why I chose this combination! :cool:
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