putting a 960 TB on a N/A 850...

Post by **tjts1** » 07 Sep 2009, 20:37

Does the plastic spark plug cover on your engine say "20 valve" or "DOHC"?

As far as I know all 20 valve 850s sold in the US had the same 65mm TB. In Canada, volvo sold a B5252 10 valve engine in the GLE trim which would have the smaller 55mm TB also found on the turbo. I don't think this is a worthwhile modification on the 10 valve engine.

Tanh · Post by **Tanh** » 08 Sep 2009, 18:20

tjts1 wrote:Does the plastic spark plug cover on your engine say "20 valve" or "DOHC"?

As far as I know all 20 valve 850s sold in the US had the same 65mm TB. In Canada, volvo sold a B5252 10 valve engine in the GLE trim which would have the smaller 55mm TB also found on the turbo. I don't think this is a worthwhile modification on the 10 valve engine.

It does say DOHC and that would mean it's a 10 valve engine, doesn't it.? My mistake on that part. Guess that would explain the weird behaviour. Not only less 1 plastic piece but also a grossly enlarged TB.

From what I have heard, the plates on the later model 850s have the plastic piece but with a 65mm diameter. Am I mistaken on that one? And if not, can I throw that in and just enjoy the improvement of having a larger TB? Or would it not be worthwhile?

Post by **tjts1** » 09 Sep 2009, 08:33

This is just a guess on my part but I suspect the aluminum wheel just above the TB that is pulled by the throttle cable on your 10 valve is different from the 20 valve wheel. This wheel is a cam that essentially determines how quickly the TB opens when you press down your foot. In order to make the 10 valve engine with a 55mm TB feel more responsive, Volvo probably fitted a very agressive cam wheel that opens the smaller TB very quickly. What you would need is bot the 65mm TB and the wheel from a 20 valve engine. Then you might see some gains and have safe throttle response.

Tanh · Post by **Tanh** » 09 Sep 2009, 11:41

Interesting, indeed!

Can anybody confirm this? I'll definitely look into this as it seems to be the best alternative yet. Thanks for the info and I'll get back to you on how well this works.

By the way, my fuel economy has taken a large hit with mod so far due to the hard response. Are there a lot of other Canadians dealing with this or am I the only one.

On another note does anybody know of other cars that use a 65mm TB and plate? 960s are a rarity where I come from so I'd have to goto the dealers to get everything.

Tanh · Post by **Tanh** » 14 Sep 2009, 12:23

Well looks like there's little getting around it. I just put a 850 throttle plate from a B5254 in instead and after a week of driving I was back to the same less responsive driving experience I had before, albeit a tiny bit faster off the line.

Turns out the 960 throttle cam (bobbin) makes no difference what so ever. My theory is that it's not the cam itself that determined the response but the engine. The 960 having an I6 with a smoother (more gradual) torque response than the I5 where the torque curve seems rather level at the lower RPMs. That might be the reason why the I5 engine pulls until it reaches it max torque at lower RPMs and really doesn't put down the same acceleration at higher RPMs. Could be wrong though. Who knows.

So the conclusion for me is that it's not worth it to do this mod on a B5252 engine, unless you plan to drag race.

Post by **demian5** » 23 Nov 2009, 15:37

Is there a mod for the turbo cars? If the NA is a bolt-on and it gets me 5mm more in size, why isn't that all over the forum too? Or did I miss something?

Tanh · Post by **Tanh** » 23 Nov 2009, 16:13

I think the reason that the turbo TBs are 55mm and not 60mm is for maintaining air velocity. I had an S80 T6 and both lines from the compressor to the intercooler were tiny in comparison to the intake lines. Having a larger than necessary hose will only slow down and decompress the air you worked so hard to compress with the turbo. Thereby defeating the purpose of turbocharging your engine.

Same theory can be applied when tuning NA engines by exhaust scavenging. Too big an exhaust for the particular engine will create undesirable back pressure and bog down the engine.

laraya · Post by **laraya** » 11 Jul 2010, 13:23

Hi, I'm Alex from Spain, I'm owner of a 1996's 850 2.5 non turbo 10 valve manual transmission non diesel. My car have a 55mm throttleplate with a plastic piece. Can I modify this and put a 65mm throttle body with a 960 plate?. The gas compsumtion will increase, Will I notice something? Bye guys.

Post by **bigdaddylee82** » 11 Jul 2010, 18:56

laraya wrote:Hi, I'm Alex from Spain, I'm owner of a 1996's 850 2.5 non turbo 10 valve manual transmission non diesel. My car have a 55mm throttleplate with a plastic piece. Can I modify this and put a 65mm throttle body with a 960 plate?. The gas compsumtion will increase, Will I notice something? Bye guys.

I'm not familiar with the 10 Valve motor, do they have the same intake manifold as the 20 Valves? I know that in the US at least there's a major difference between '94 and '95 intake manifolds, but they still use the same throttle body. I also know that there are a lot of the turbo car guys on Volvospeed.com that either swap an entire NA intake manifold onto their car or bore out the throttle opening in the turbo manifold to fit the NA throttle body and 960 plate. I don't know if any of that helps you, but that's what I know.

- Lee

laraya · Post by **laraya** » 16 Jul 2010, 11:49

Hello:
Last weekend I opened my 1996 car for putting a 94's body throttle with 65mm repaired plate and: My car has a 55mm throttle body with the plastic piece and the tube from the air filter is little for the new throttle body.
If I do the change to 65mm throttle, what things may occurs?

putting a 960 TB on a N/A 850...

Re: putting a 960 TB on a N/A 850...