Sprint or 2lt engine?

UKPhilTR7 · Postby **UKPhilTR7** » 20 Feb 2008 08:55

Which is beetter to have in a TR7 a sprint or a 2lt engine? I have a 2lt at the moment, but I am thinking of going for a sprint.

Dave Dyer · Postby **Dave Dyer** » 20 Feb 2008 09:14

Phil,
Technically speaking they are both 2ltr!! The sprint would only give you a small power gain for the work involved, plus getting a 'good one' may be a problem. If a small power gain is what your after then you could mod the engine you have now i.e. exhaust, cam, gas flowed head, carbs etc. but at a cost. I'm sure other guys will tell you to go down the V8 route.
Is it the power your after or a new project ?

Dave

UKPhilTR7 · Postby **UKPhilTR7** » 20 Feb 2008 09:37

Hi Dave,
I have put a few things on my 2lt such as K&N filters, a newer fuel pump and bits like that, but I did think that the sprint was much better in performance. But if it is not much of a difference that I do not think I will put muself through all the pain lol.
I was thinking of putting BAL needles in her now as I have heard that they are good with K&N's. do you know if this is true?
Cheers,

Philip · Postby **Philip** » 20 Feb 2008 09:51

better go for a fast road conversion on the standard two litre - higher lift cam, reworked head, 45DCOE weber carbs with K&N filters, 4 branch exhaust.

Might not go much quicker but it sure makes a nice noise !

Still standing !

TR Tony · Postby **TR Tony** » 20 Feb 2008 10:06

Phil, the real difference with the Sprint engine vs the 8V engine is not so much the extra BHP but in the way the power is delivered. The 8V tends to run out of steam as you get past 4500 rpm, whereas the 16V revs much more freely & should pull right through to the red line.

Our good friend Beans has a lot of experience with the Sprint engine & may be able to offer you some feedback on how his car drives compared to an 8V.

Both motors have scope for tuning & potentailly you could get more BHP from the 16V, but then that depends how deep your pockets are.

With your K&Ns, you may find that you need to go a stage richer on the needles. I think BAL is the suggested change. What are the plugs like now?

Tony

1981 2L FHC Cavalry Blue - very original & not rusty!
1980 3.5L V8 DHC Regency Red - on the road again.

UKPhilTR7 · Postby **UKPhilTR7** » 20 Feb 2008 10:47

I must admit that my plugs are getting black easy now and they really smell of petrol. When I wire brush them off they are OK for a little, but then will need cleaning again. I have tried turning down the idle revs down a little, but really think she will need a tune now and was thinking of getting in the BAL before the tune is done.

Orophin · Postby **Orophin** » 20 Feb 2008 17:12

Cost wise I think it's better to go sprint, but i bet it's a little easier to just tune the slant 4 engine. When you say you want a better engine, what does that mean? More bhp? Sprint engines area about 130bhp standard contrasted by the slightly embarising yet sometimes surprising 105bhp from the slant 4. They both have tuning potentual but you may as well v8 it? That's alot of work though. As a whole I would say the sprint engine is better than the slant 4. Is the slant 4 just a bored out 1850cc dolly engine?

TR Tony · Postby **TR Tony** » 20 Feb 2008 17:46

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by UKPhilTR7

I must admit that my plugs are getting black easy now and they really smell of petrol. When I wire brush them off they are OK for a little, but then will need cleaning again. I have tried turning down the idle revs down a little, but really think she will need a tune now and was thinking of getting in the BAL before the tune is done.
<hr height="1" noshade id="quote"></blockquote id="quote">
If your plugs are black now, then don't change to richer needles! Sounds like the carbs need a good tune up. The idle speed screw won't change the overall mixture, to do that you need to adjust the jets from the bottom of each carb.

I would get the mixture set up better first, then if you find that it is too lean through the rev range then you can look at changing the needles. Changing the needles is pretty simple so it wouldn't be too much extra work - you may not need it though.

Tony

1981 2L FHC Cavalry Blue - very original & not rusty!
1980 3.5L V8 DHC Regency Red - on the road again.

Beans · Postby **Beans** » 20 Feb 2008 18:07

The standard TR7 and the Sprint engine actually are one and the same (2.0 litre) engine [}:)]
Only real difference is the cylinder head (and of course everything that's related to it such as timing gear, pistons etc.)
As stated by the others, what are you after?

Personally I think tuning a standard TR7 lump to 130-135 bhp should be no real problem. You only have to work on the head itself, some better shaped valves, other cam and a pair of new needles in the carbs.

And as you can (hopefully) see in the picture above there is room for improvement in the standard TR7 head. Also this will probably be much cheaper then converting to 16v's.

Unless you buy a cheap Sprint engine and just drop it in ... [:I]

<center>

1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (not very well known yet, but back on the road)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC
http://tr7beans.blogspot.com/</center>

Beans · Postby **Beans** » 20 Feb 2008 18:21

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by TR Tony

...Beans has a lot of experience with the Sprint engine & may be able to offer you some feedback on how his car drives compared to an 8V <hr height="1" noshade id="quote"></blockquote id="quote">
Actually some experience with both engines in tuned form ...
My Sprint engine in 't Kreng produces Â±175bhp @5800rpm and 197Nm @4500rpm of torque. Will happily rev to 7000 rpm in the lower gears;
8 Valve engine in the DHC produces Â±135bhp @5500rpm and 176Nm @4100 of torque (standard TR7 torque figure of 161Nm is reached @2900rpm).

Some more info here ...

http://www.forum.triumphtr7.com/topic.asp?TOPIC_ID=6463

<center>

1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (not very well known yet, but back on the road)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC
http://tr7beans.blogspot.com/</center>

UKPhilTR7 · Postby **UKPhilTR7** » 20 Feb 2008 20:02

Cheers guys.
Tony you mentioned 'to do that you need to adjust the jets from the bottom of each carb.' Can you tell me a little bit more about this as I am sure that I messed about with this some time ago, to try and sort things out. Think I made it a little worse[}:)]
Is it a simple job? And if so how would I go about it?

saabfast · Postby **saabfast** » 20 Feb 2008 20:28

UKPhil, do you have a Haynes manual - they are pretty cheap on the bay of bits and give a reasonable background to the carbs and tuning, probably also in the works manual available on jclays site.
The needle, set in the piston, is tapered and drops into the jet, varying the orifice for fuel flow according to the revs/air flow. The jet is adjusted up and down by the nut on the base of the carb. Screwing it in pushes the jet up the tapered needle reducing the opening for the fuel flow and making the mixture weaker, unscrewing does the reverse and richens the mixture. Ideally, the carbs should be synchronised for air flow first (Gunsons do a cheap meter), then the mixture set. Some carbs have a lifting pin on the side to check the mixture setting, however on mine they are always too rich when set correctly using the lift pin. When you lift the pin the revs should rise slightly then settle to normal. If the revs continue to rise the mixture is too rich, if the car stalls it is too weak. At the end, reset the idle speed.
This is very much a simplification, a manual will help you.

Alan
Saab 9000 Stg 1
'81 TR7 DHC

TR Tony · Postby **TR Tony** » 20 Feb 2008 21:00

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by UKPhilTR7

Cheers guys.
Tony you mentioned 'to do that you need to adjust the jets from the bottom of each carb.' Can you tell me a little bit more about this as I am sure that I messed about with this some time ago, to try and sort things out. Think I made it a little worse[}:)]
Is it a simple job? And if so how would I go about it?
<hr height="1" noshade id="quote"></blockquote id="quote">

Phil, it is quite a straightforward job & Alan's summary above gives you the basics. There is a bit more detail to it all so it would be worth getting a Haynes manual or a copy of the factory repair manual so you can do the job correctly. Or have a look at this link:

http://www.mintylamb.co.uk/?page=sutune.htm

This guy is talking about twin SUs on a Spitfire but the procedure is much the same.

Good luck!

Tony

1981 2L FHC Cavalry Blue - very original & not rusty!
1980 3.5L V8 DHC Regency Red - on the road again.

UKPhilTR7 · Postby **UKPhilTR7** » 21 Feb 2008 09:39

Thanks for this guys the description and link is great, think i will have a look at it this Sundat and see what I can sort out, but still keep her booked in for the tune, to get her totally sorted out, but it is nice to know how to do this so I can try. Cheers, Phil

jclay (RIP 2018) · Postby **jclay (RIP 2018)** » 21 Feb 2008 13:47

Before you start to adjust the carbs, be sure to check all vacuum hoses and connections to the manifold. Especially check the banjo bolt that holds the brake vacuum line to the manifold. You will never get the carbs adjusted properly if there is an air leak in the system.

You can download this article from my download site.
Steps for Tuning SU Carburetors.doc:
[url="http://homepage.mac.com/WebObjects/FileSharing.woa/3/wo/uTxwKeQxCGk4rEkm.1/0.2.1.2.26.31.97.0.35.0.1.1.1?user=jclaythompson&fpath=Triumph_Articals&templatefn=FileSharing4.html"]Clay's download site[/url]

Anonymous

Sprint or 2lt engine?

Sprint or 2lt engine?

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