Lotus Elan

How much HP

PostPost by: Certified Lotus » Wed Dec 10, 2014 11:35 am

Rohan, you are very close to the spec my engine is being built on. Details to follow soon.
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PostPost by: bill308 » Thu Dec 11, 2014 10:53 pm

The best USA East Coast engine builders are now specifying the Stowe head (from DBE) on their customer cars. The intake ports are very straight and the head bolts are supported by cast in compression columns. John Stowe is a retired P&W Aircraft pattern maker and long term racer turned foundry owner. Steve Jennings, of Jennings Racing in UT, also recommends the Stowe head and this was the head he provided for Jay Leno's reported 220 bhp 26R alloy engine project. Peter Marcovicci of Marcovicci-Wenz Engineering in Ronkonoma, NY, specified 1.625 intakes and 1.375 exhaust valves on my 2-liter alloy block engine with a Stowe head. I asked if it was an oversight not to specify 1.4 exhaust and he said no. My engine will be a street engine with occasional track use. The cam is TBD at this time, but the target is 190 bhp and similar torque. Good road manners are very important to me.

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PostPost by: rgh0 » Fri Dec 12, 2014 1:05 am

Is the Stowe head the one with the half moons in the centre spark plug well like the original die cast heads?

I dont think 1.375 versus 1.4 inch on the exhausts makes much difference unless you have an open wheeler race car with a very big and free flowing exhaust. People tend to use what they have easily available I think

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PostPost by: bill308 » Fri Dec 12, 2014 4:17 am

Rohan.

Not sure about the half moons in the center spark plug well as I haven't received mine yet. They are sand cast. To date, there were a small number that John Stowe cast and machined for DBE. Dave bought the tooling and they are now cast by Buddy Bar and machined by an outside source. Dave currently has several on the shelf. The heads are sold without valve guides and seats installed as different racing organizations have different hardware requirements.

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PostPost by: rgh0 » Fri Dec 12, 2014 6:10 am

Hi Bill

Saw a new head that had the half moons on an open wheeler at a recent race meeting. It had nice big inlet tracts like the SAS head however that head does not have the half moons. The owner was not saying where he got it from.

I guessed they put the half moons in to make it similar to the early heads to assist approval to use on early race cars despite the big inlets !

I presumed it was the new head that was being made in the USA as I had not seen one like it before. It would be good to get some detailed photos when you get yours

cheers
Rohan
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PostPost by: CBUEB1771 » Fri Dec 12, 2014 2:59 pm

Rohan,
I have seen a couple of the "Stowe" heads at Bill McCurdy's (Williams Racing) shop here in the Boston area. These were early ones cast in Connecticut before the deal was done with Dave Bean. These were made for 10 mm spark plugs to leave more material between the plug and the inlet valve seat. I don't know if that was something you might have noticed. That is the most obvious externally visible feature that comes to my mind.
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PostPost by: bill308 » Fri Dec 12, 2014 4:32 pm

Thanks for that Russ.

Monday I placed a preliminary order for one of the new heads but delayed shipment pending some additional items. In the mean time, it was determined that my new (old/used) BDP alloy block was porous, after removing the old sleeves, to the point that it was too risky for me to take a chance on reworking it. The seller is looking at trading me for his backup BDP block (in better overall shape and already at 90-mm) as compensation, but asked if I would also be interested in his early Stowe head. I said yes, not knowing there was any difference in the heads. I'll have to ask John when I next see him.

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PostPost by: CBUEB1771 » Tue Dec 23, 2014 2:07 pm

I spoke to the people at Dave Bean yesterday about the Stowe heads and confirmed that the normal specification is still for 10 mm spark plugs however the casting can be machined for 14 mm sparks plugs and that is an option. Unfortunately Dave Bean has decided for the time being that only the large inlet tract version will be offered. I was told this is fine for a 1600 cc race engine but not good for road use unless you go up to something close to 2000 cc and EFI so that fuel flow is not governed by our friend Bernoulli. So this is nothing I am interested in. At least the Stowe heads are made to accept the normal shell bearings for the cams. I really don't like the SAS solution of running the cams directly in the machined casting, that is fine for an engine designed in 2014 but not one running carburetors and an ancient temperature control system.
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PostPost by: gjz30075 » Tue Dec 23, 2014 2:33 pm

If all that is 'wrong' with the head are large inlet tracts (for street purposes), would it be worthwhile (and maybe cheaper/easier) to fab up an insert of sorts to cut the size of the inlet tract down a bit?

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PostPost by: rgh0 » Tue Dec 23, 2014 10:21 pm

I would not be so negative about big inlet tracts for a road car and 1600 cc. As long as you stick with a relatively short duration high lift cam and an high enough compression ratio I would have thought you should be OK.

Maybe a little less tractable than an original head in the 1000rpm to 2000 rpm range especially when cold but beyond that I don't think you will notice much difference and above 3000 to 4000 rpm the benefits are huge. This is based on my experience with the big inlet stage 4 Omnitech / John McCoy conversion. John also does a stage 3 road porting that has slightly smaller porting.

I would have thought Dave Bean / Stowe would have done some dyno runs to enable a quantitative comparison

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PostPost by: bill308 » Mon Dec 29, 2014 2:55 pm

I asked John Stowe, "Other head manufacturers offer a small bore and large bore head design for street and track use. How would you characterize the bore of your inlet and exhaust ports?"

John responded, "Hi Bill,

It is a fairly large bore; however, it is substantially re-shaped, particularly in the area from the valve guide to the seat to reduce turning losses at the valve. FIA race engines are required to use a 1.562? inlet, and English customers have done well with this setup. The head was designed for American Formula B, so it was designed around 1.625? to 1.7? valves. For the street, choose the former for most applications, and the latter if you are at or near 2 liters. Do not enlarge the choke point at the valve stem for a 1600; just smooth the port and blend to the seat. A short duration, fast lift cam will provide good low end drive ability and good top end power. Good big valve 1600cc FB TCs make over 150 ft/lbs torque and around 190 @ 8200, and 210-220 at 8500.

Happy Solstice!

John"

Thanks John.

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PostPost by: Famous Frank » Tue Dec 30, 2014 4:03 am

Back to the original question, how much HP will the gearbox take, a simple answer is: ......... More than the diff stub axles. I love doing burn outs and even with a strong little 1600 with 130 HP, I've broken the stub axles.

Forged units will stop that from happening but the weak points will keep moving up the ladder. Make your tires be the weak point and the other parts will last much longer!

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PostPost by: tasswipe » Tue Dec 30, 2014 1:58 pm

my old elan sprint was fitted with an all steel 1800 tc based on a south african 1760 tall block,this block had more meat for a true 1800 motor.

it had mahle pistons and had a full brm phase 5 head and was dry sumped.
it ran 48 webers/facet pump and a modded s1 rad too

it ran a quaife box /4.1 lsd and tony tompson drivegear/exhaust system

the engine was built by paul fisher[ex brm]in 1992.,and at the time cost around 10k to build
it measured 212 bhp on hall and fowlers engine dyno and later when tested on pat thomases rolling road [kelvedon mtrs]it showed 168 rwhp.

the newer front water pump covers we not available at the time ,so a toothed belt system was cobbled up but it was the engines weak point.

i loved that engine

how ever the car was destroyed in an attempted theft in july 93 .the engine was recovered and rebuilt

tony thompson bought it cheaply off me/paul and it ended up in a 26r [replica] owned and raced by a singapore airlines pilot.
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